Encyclopaedia Index

I ICEM-CFD IF..then..else..endif IBUOYA/B/C ICHR ICNGRA/B/C ICOLOA IDBCMN/IDBFO/IDBGRD IDISPA/B/C/D IENUTA

IF IFREQU IG IGES INTERFACE IGR IHOLA ILATGA IMAT IMB1/IMB2 Imbalance Patch IMON IMMERSOL IMON IMPLICIT FORMULATION

INADVERTENT INFLOW INCHCK INCL INCLUDEd COMMON files INDEPENDENT TIME FLOWS INDVAR INFLO INFLOW_Boundary_Condition INFOrmation-seeking_PIL_commands

In-Form

Inforout file

INIADD INIFLD INIPLN INIPOL INIT INITIAL_Conditions INIVAL INLET Object INLET INNER_ITERATIONS

Input-File Library INPUT SOURCES INSTRUCTION STACK INTEGER INTEGRATION INTERFACE INTERFACIAL INTERPHASE_DRAG INTERPOLATION INTERVALS

INTFCO INTFRC INTMDT INTMTR INTRC1 INTRC2 INTRPT INTSOR INTTYP INTVL1 INTVL2

Inverse-problem solver

IOPTN IPARAB IPLTF IPLTL IPORIA/IPORIB IPRN IPROF IPROP IPRPSA/IPRPSB IPSA IREG IROTAA IRUN
ISGx
ISKINA/ISKINB ISLN ISO ISOLBK ISOLX ISOLY ISOLZ ISTDB1/ISTDB2 ISTEP ISTPRF ISTPRL ISWC1 ISWDB1/ISWDB2 ISWEEP ISWPRF ISWPRL ISWR1/ISWR2

ITABL Iteration frequency for user-defined blocks, setting the

ITHCL ITHDB1/ITHDB2 ITHYD ITIMA/B/C IURINI IURPRN IURVAL IVARBK IVRMCO
IWSR, i.e. Ideal Well-Stirred Reactor
IX IXF IXL IXMON IXPRF IXPRL IY IYF IYL IYMON IYPRF IYPRL IZ IZDB1/2 IZF IZL IZMON IZPRF IZPRL IZSTEP IZW1


I location, index for specifying

(see IMON)


ICEM-CFD

ICEM-CFD... a grid-generation and data-input package, developed by Control Data Corporation.

An interface exists between ICEM and PHOENICS.

See "What's new in PHOENICS 3.3 ".


IBUOYA

--------- PIL integer; group 13 ---------

IBUOYA... is used to carry a variable name into GREX to use as a criterion for activating certain storage.

See GREX3 for further information.


IBUOYB

--------- PIL integer; group 13 ---------

IBUOYB... is used to carry a variable name into GXBUOY and BFCGR so that the value part of the gravitational source term may be calculated as a linear function of this and one other variable.

See GXBUOY and BFCGR for further information.


IBUOYC

--------- PIL integer; group 13 ---------

IBUOYC... is used to carry a variable name into GXBUOY and BFCGR so that the value part of the gravitational source term may be calculated as a linear function of this and one other variable.

See GXBUOY and BFCGR for further information.


ICHR

------ PIL integer; default=2; group 23 --- -

ICHR....controls the print-out of contour-plot levels as follows,

ICHR=1 signifies that even numbers are used; ICHR=2 signifies that odd numbers are used; ICHR=3 means that both even and odd numbers are used.


ICNGRA

--------- PIL integer; group 8 ----------

ICNGRA... is used, when the Conjugate Gradient solver in GXCNGR is activated, to select whether a preconditioning is (ICNGRA=1) or is not (ICNGRA<>1) to be used.


ICNGRB

--------- PIL integer; group 8 ----------

ICNGRB... is used to select the first variable, in addition to first-phase pressure and velocities, to be solved using the Conjugate Gradient solver, GXCNGR.


ICNGRC

--------- PIL integer; group 8 ----------

ICNGRC... is used to select the last variable, in addition to first-phase pressure and velocities, to be solved using the Conjugate Gradient solver, GXCNGR.

ICOLOA

----------- PIL integer Switch ----------

ICOLOA... is used to activate the interpolation schemes for the cell-face velocities for CCU.


IDISPA

------- PIL integer; groups 1 & 19 ------

Use for parabolic and x~y~transient simulations

IDISPA, when greater than 0, specifies the frequency, in terms of z-steps for PARAB=T and of time steps for STEADY=F, at which x-y fields of variables are dumped to the parphi (or parada) file by way of GXPARA, called from GREX, for plotting by VR-Viewer or PHOTON.

Use for other transient or steady calculations

IDISPA also specifies the frequency, in terms of isweeps for steady elliptic simulations, and of time steps for transient calculations, at which fields of variables and the grid are dumped to the PHI(or PHIDA) and XYZ(or XYZDA) files by way of DUMPS, called from GREX, for plotting by way of VR-Viewer or PHOTON.

The names of the dumped files can be customised by setting CSG1 and CSG2 in Q1.

In transient cases, the first character of CSG1 is used together with the timestep number to generate the name of the dumped phi (or phida) file e.g. if CSG1=A, the files will be A1, A2, A3 etc (or A1DA, A2DA for phida files). The files are written at the end of each step. Adding 'IN' after the letter (CSG1=AIN) will cause the initial fields to be dumped to A0.

For BFC cases the first letter of CSG2 (if set) is used to derive the name of the dumped grid file.

In steady cases, CSG1 must be set to SW, otherwise no files will be dumped. The file names will be S1, S2 S3 etc. CSG1=SWIN will generate a file of the initial values, S0.

Setting CSG1=SW in a transient case will cause files to be dumped each for sweep of each timestep, each step overwriting the files from the previous step.

Choosing one or the other

x~y~transient simulations can use either method of dumping.

It is the first, i.e. parabolic, mode which is active whenever CSG1 is not set.


IDISPB

--------- PIL integer; group 9 ----------

IDISPB, in addition to specifying the first (z or time) step at which dumping by GXPARA occurs, determines the first sweep or time step at which PHI(or PHIDA) and XYZ(or XYZDA) are dumped by way of DUMPS. The default value of 0 means start at the first sweep or step.

IDISPB was also used in GXHOL to specify, for STEADY cases for which the Height Of Liquid method is activated, the first sweep at which the VFOL variable is updated. See HOL and the encyclopaedia for further information. This use is replaced by SPEDAT(SET,HOL,IFIRST,ifirst)


IDISPC

--------- PIL integer; group 9 ----------

IDISPC, in addition to specifying the last (z or time) step at which dumping by GXPARA occurs, determines the last sweep or time step at which PHI(or PHIDA) and XYZ(or XYZDA) are dumped by way of DUMPS. The default value of 0 means no limit.

IDISPC was also used in GXHOL to specify, for STEADY cases for which the Height Of Liquid method is activated, the frequency in sweeps at which the VFOL variable is updated. See HOL and the encyclopaedia for further information. This use is replaced by SPEDAT(SET,HOL,IFREQU,ifrequ)


IDISPD

--------- PIL integer; group 19 ---------

IDISPD, when greater than 0, specifies the frequency, in terms of z-steps for PARAB=T and of time steps for STEADY=F, at which fields of variables are dumped to the Pxx files and ,for BFC=T, grids are dumped to the Xxx files, for viewing in PHOTON, between the values of IDISPB and IDISPC (See PHENC entries on these)


IENUTA

------ PIL integer; groups 1, 9 & 13 -----

IENUTA... is used to control turbulence-model options, in Satellite, GREX and EARTH.
IENUTA

Turbulence model

1 RNG high-Re k-e model
2 Chen-Kim high-Re k-e model
3 Lam-Bremhorst low-Re k-e model
4 Chen-Kim low-Re k-e model
5  
6 Simple eddy-viscosity multiplier for low Reynolds numbers
7 Two-scale high-Re k-e model
8 Two-layer low-Re k-e model
9 Another simple eddy-viscosity multiplier for low Reynolds numbers
10 Wilcox-Kolmogorov high-Re k-omega model
11 Wilcox-Kolmogorov low-Re k-omega model
12 MMK high-Re k-e model
13 Kato-Launder high-Re k-e model

See help on TURMOD and TURBULence for further information.

wbs


IF

---------------- Advanced PIL command --- -

First element of the PIL IF construct.

The PIL IF construct is used in two circumstances. One is to exit from loops (see the entry on LOOP) and the other is the FORTRAN-like IF..THEN..ELSE..ENDIF explained here.

The syntax of the block IF is:


    IF <logical expression> THEN

    <PIL statements 1>

    ELSE

    <PIL statements 2>

    ENDIF

For example: IF (NX.GT.1) THEN + SOLVE(U1) -----> PIL statement ELSE + SOLVE(V1) -----> PIL statement ENDIF

The <logical expression> has a syntax and capability are very similar to the corresponding FORTRAN construct, with the following differences:

  1. There is no precedence on the operators .AND. .OR. and .NOT.; it is therefore recommended that brackets are used to remove potential ambiguities.
  2. A .NOT. must not immediately follow an .AND. or .OR. but must be preceded by a bracket. Eg (CARTES.AND..NOT.NONORT) is illegal and must be written as (CARTES.AND.(.NOT.NONORT))
  3. String constants are not enclosed by quotes; but string variables should be enclosed by colons

    IFs can be nested to a maximum depth of 20.


IFREQU

When the graphical monitor is in action, the solver module checks whether the keyboard has been used every IFREQU sweeps. IFREQU is defaulted to 10; but, since for a large-grid case each sweep may take several seconds, the user may desire more frequent checking.

This can be achieved by placing the following statement in the q1 file:

SPEDAT(MONITOR,IFREQU,I,the desired value).


IG

-------- PIL integer array; default=0; group -

IG....is an array for transferring to GROUND any integer data that the user may need there.


IGR

IGR, an integer set by EARTH to dictate which part (group) of GROUND, GREX3, etc is to be entered.

See PHENC: GROUND.F


IHOLA

----- PIL integer; groups 1, 8, 9, 13 & 19 -

IHOLA... is used, for the Height-Of-Liquid method for free-surface flows, to specify the direction along which the liquid height should be measured. See the help and encyclopaedia entries on Height of liquid for further information.


ILATGA

----- PIL integer; group 13 ---------

ILATGA... is used by GXLATG in the calculation of horizontal gravitational forces resulting from differences in a liquid-layer depth in a pipe. The constant is used to define the direction in which gravity acts. See the help on GRAV for further information.


IMAT

IMAT is the "material index" showing the position of the property data in the PROPS file. It is conveyed to EARTH via the PRPS field. See PHENC entry PRPS.


IMB1

------ PIL integer name; group 7 ----------

IMB1.... indicates which whole-field store will be used for the continuity imbalances of phase 1 in response to the command STORE(IMB1). Units are mass/time. Display of the field of continuity imbalances can be useful in isolating areas of the integration domain where the imbalances remaining are largest. Sometimes just a few cells can contain all the errors: once such zones are located, PATCH-wise under-relaxation can be used over them to promote faster convergence.


IMB2

------ PIL integer name; group 7 ----------

IMB2.... indicates which whole-field store will be used for the continuity imbalances of phase 2 in response to the command STORE(IMB2). See IMB1 for further information.


IMMERSOL

IMMERSOL , the method of handling simultaneous radiation and conjugate heat transfer in complex circumstances.
See PHENC entry: Radiative Heat Transfer in PHOENICS; section 3


IMON

------ PIL integer; default=1; group 6 ----

IMON....index for specifying I location ( in BFC nomenclature ) at which the coordinates:

are displayed for sweep-by-sweep monitoring in the course of grid generation by the "Laplace solver", MAGIC(L).


IMPLICIT FORMULATION of finite-volume equations

The finite-volume equations solved by PHOENICS (see PHENC entry) include algebraic formulae for FP, the value of variable F at point P, in terms of the values of F at the nort, south, east, west, high and low neighbouring cells, i.e. FE, FW, FN, FS, FH, and FL.

If these neighbour values of F are those which prevail at the current time step, the "implicit formulation" is said to be in use. This is what is used when N is entered as the 6th argument of SOLUTN; it is the default; and it is recommended for general use.

When Y is entered as the 6th argument, the neighbour values are taken as those which prevailed at the end of the previous time step, the "explicit formulation" is said to be in use. This option may be used to effect computer-time economies when the so-called "Courant criterion" is satisfied, namely u*dt/dx <1, where dt and dx refer to the time and space step sizes and u is the velocity.

One may wish to select for explicit treatment those variables which change much more slowly with time than other variables, again for reasons of economy.

See PHENC entry: schemes


INCHCK

---- PIL integer; default=1; group 25 --- -

INCHCK....element number of F-array, the value of which is checked to be greater than SMCHCK and less than BGCHCK. The number may be obtained by setting DBINDX=T.


INCL, a PIL command

Insertion of INCL(file_name , on a single line in a Q1 file, with or without a closing bracket, will load the named file into the instruction stack with the same effect as though the contents of the file resided in the Input-File Library.

If lines containing TALK=... or STOP are present in the file, these lines will be ignored. Q1's can therefore be "swallowed whole".

This feature enables users to use the same set of instructions in many different Q1 files, without having to copy them in.

The so-loaded file can itself contain l( or incl( commands.


Independent time flows, setting of

(see STEADY)


Independent variables

In general, a phenomenon simulated by PHOENICS will be four-dimensional, the four dimensions being time, and three space dimensions. The latter are called, for ease of reference: north-south; east-west; and high-low. Specifically:


INDVAR

------------------------------------

Ground integer.

INDVAR....is the number of current dependent- or auxiliary- variable number.


INFLO

----- PIL real flag; value= 23.0; group 13 -

INFLO....is a PATCH type used to specify PATCHes at which only inflow is desired. Thus, where a pressure boundary condition prevails at such a PATCH, cell pressures in excess of the outside pressure do not cause outflow.


INIADD

---- PIL logical; default=F; group 11 --- -

INIADD....controls whether or not the initial fields which are set by way of FIINIT, PATCH and INIT are additive over intersecting PATCHes.

When INIADD is T, they are added.
When INIADD is F, they are not added, and the last PATCH overwrites what is implied by FIINIT and any preceding PATCHes.

The CONPOR command unconditionally resets INIADD to F.

It is also set to .FALSE. in EARTH, whenever PRPS is stored and its value is set to a value which is present in the PROPS file; for the addition of such values can have no physical significance.


INIFLD

---- PIL logical; default=F; group 21 --- -

INIFLD....may be set to T if it is desired that the initial fields should be printed. See FIINIT to learn how these are set.


IniPln

(Stream Menu)------------------------------------- Photon Help ----

[IniPln] specifies the initial seeding plane. All streamlines will be drawn from this plane.

See also: [Set]


INIPOL... a reserved patch name.

When the grid is cylindrical polar, and it is desired to create an initial velocity field which is uniform, the following provisions in the Q1 file will have the desired effect:


INIADD=F
PATCH(INIPOLxx,INIVAL,1,NX,1,NY,1,NZ,1,1)
INIT(INIPOLxx,U1,0.0,GRND)
INIT(INIPOLxx,V1,0.0,GRND)
FIINIT(V1) = absolute velocity in the XY plane
FIINIT(U1) = angle (in radians) between the direction of the velocity and the (angular )x-axis


INIT

------ Command; group 11 --------------

INIT....is a command used for setting PATCH-wise initial conditions. It has four arguments.

Initial values may be inserted, PATCH-wise, by means of the commands PATCH and INIT. In the former, INIVAL must be inserted as the second entry, thus:

PATCH(patch name, INIVAL, first IX, last IX, etc ) .

Then the INIT command follows, for all variables which it is desired to set in this way, as:

INIT(patch name, variable name or index, ZERO, value ) . See the Encyclopaedia entry: INITIAL CONDITIONS.


INIVAL

---- PIL real flag; value= 26.0; group 11 -

INIVAL....is a PATCH type used in group 11 for specifying zones of constant initial values specified for a given-field variable by the 4th argument of INIT.

See INIT for further information.


INLET, a PHOENICS-VR object type

An INLET object defines an area of fixed mass flow. The mass flow can be specified as:

  1. density and velocity; or
  2. density and volumetric flow rate; or
  3. massflow
The direction of the massflow (inflow or outflow) is set by the sign of the velocity or flow rate. See the description in the PHOENICS_VR Reference Guide, TR326

INLET

----- Command; group 13 --------------

This command is used to declare inlets, i.e. fixed-mass-inflow boundaries. Used in conjunction with VALUE it does no more than can be done via PATCH and COVAL, but is slightly more compact and conceptually easier to deal with.

As well as the mass-flow rate per unit area, non-zero values of velocity and scalar quantities convected in by the mass flow can be specified by the VALUE command. See the entry on VALUE for more information.

The syntax is : INLET(NAME,TYPE,IXF,IXL,IYF,IYL,IZF,IZL,ITF,ITL)

NAME is a unique identifier for the INLET, up to 8 characters in length. TYPE can be NORTH,SOUTH,EAST,WEST,HIGH or LOW, and specifies which cell face areas will be used to multiply the mass-flow set. IXF ... ITL specify the limits in space and time over which the mass source is to be active. Thus :

REAL(WIN,RHOIN); WIN=3; RHOIN=1.0
INLET(INL1,LOW,1,NX,1,NY,1,1,1,LSTEP)
VALUE(INL1,P1,RHOIN*WIN) ; VALUE(INL1,W1,WIN)

specifies an INLET extending from IX = 1 to NX, IY = 1 to NY at IZ = 1, active over all time steps, in which mass is entering the LOW faces of the cell at a rate of RHOIN*WIN/unit area.

The function of the command is to generate a PATCH with the NAME and TYPE specified over the set limits. COVALs are also generated for all solved variables, with ONLYMS,0.0 for the COefficient and VALue, except for P1 (and P2 if .NOT.ONEPHS) which has COefficient FIXFLU, VALue 0.0.

See the entries on SOURCE, PATCH, COVAL, TYPE and FIXFLU for further details.


Inlets, declaring of

(see INLET)


Inner iterations, specifying number of

(see LITXC)


Inner radius, specifying the

(see RINNER)


Input sources, simplification of

(see IURVAL)


Input Window

------------------------- Input Photon Help ----

[Input Window] is used to type in the coordinates of each point of the geomentry.


Instruction stack, clearing the

(see CLEAR)


INTEGRATION

The solution of the differential transport equations is sometimes called (numerical) integration of the equations.


Integration domain, specifying length of

(see XULAST)


Integration domain, specifying the number of sub-divisions in

(see NX)


Interface value of variables

(see PHINT)


Interpolation

(see Alternative Interpolation Schemes.)


Intervals

---------------------------------- Photon Help ----

[Intervals] shows the number of intervals if the current CONTOUR element was drawn with isolines.


Intervals, setting of

(see GRDPWR command)


INTFCO

Integer used in GXIFRIC to denote interphase friction coefficient.


INTMTR

Integer used in GXIMAS to denote interphase mass-transfer rate.


INTRC1

Integer used in GXIDIF to denote phase-1 to interface transfer coefficient.


INTRC2

Integer used in GXIDIF to denote phase-2 to interface transfer coefficient.


INTVL1

Integer used in GXIVAL to denote interface value for a first-phase variable.


INTVL2

Integer used in GXIVAL to denote interface value for a second-phase variable.


IOPTN

--------------------------------------

IOPTN....holds the value of the PHOENICS option which has been installed, and which governs the capabilities of PHOENICS which may be activated.

>>> See also the Encyclopaedia entry 'OPTIONS'.

The value of IOPTN is "locked" into EARTH at the time of installation, and cannot be changed by the user.


IPARAB

---- PIL integer; default=0; group 14 --- -

IPARAB....specifies the pressure-boundary type for parabolic calculations ( i.e. PARAB=T ).

IPARAB=0 instructs EARTH to deduce the pressure downstream of each z slab, by reference to total mass continuity. This option is for use in flows whose lateral ( i.e. x-wise and y-wise ) boundaries are confined ones ( as in pipes and ducts generally ).

Other options are:

  1. IPARAB=1 means that the pressure downstream of each z slab is set by the parameter PBAR. This option is for parabolic calculations in which the lateral boundaries are unconfined ( as in boundary layers, jets, wakes and etc ). It is the user's responsibility to specify the downstream pressure, by way of PBAR.
  2. IPARAB=2. This is like IPARAB=1; but in addition, it implies that the pressures to be used in the x-direction momentum equation are also fixed.
  3. IPARAB=3. This is like IPARAB=2; but it is the y-direction momentum equation which employs fixed pressures, not the x-direction one.
  4. IPARAB=4. This option can be used for hyperbolic calculations. Unlike the other options, when IPARAB=4 the z-direction velocity is influenced by the lateral pressure variations, rather than just the slab-to-slab average. It should be used only when the z-direction velocity everywhere exceeds the local velocity of sound. Library case 156 makes use of this option.
  5. IPARAB=5. This option is useful when a supersonic jet emerges into a subsonic atmosphere, as for example at the downstream end of a rocket motor. A test is then made at each location as to whether the velocity is super- or sub-sonic; and the formulation of the finite-domain equations is correspondingly altered, so as to maintain uniformity of pressure, across the stream, in the subsonic region.

IPLTF

----- PIL integer; default=1; group 23 --- -

IPLTF....first sweep for plots of spot values and residuals.

On restart runs, this should be set to FSWEEP in order to avoid the allocation of a segment of EARTH storage for the information from 1 to FSWEEP-1 which will not be used.


IPLTL

----- PIL integer; default=-1; group 23 -- -

IPLTL...last sweep for plots of spot values, etc. The default of -1 ensures that if the user has not set IPLTL, EARTH will set it to LSWEEP ( or to LITHYD if PARABolic ).


IPORIA

------- PIL integer; group 11 & 19 ------

IPORIA... is used in the specification of porosities that depend, dynamically, upon pressure for cells for which IZ is no greater than IPORIA.

See the help and encyclopaedia entries on POROSI, and GREX3, GXHOL, GXPORA and GXSURF for further information.


IPORIB

--------- PIL integer; group 11 ---------

IPORIB... is used in the initialisation of porosities to simulate different fixed geometries.

See the help and encyclopaedia entries on POROSI, and GREX3 and GXPORI for further information.


IPRN

------- PIL integer array ----------------- Read only.

Internal storage of information set by OUTPUT command.

The settings of IPRN are based on prime numbers. ISLN(PHI) divisible by 2, 3, 5, 7, 11, 13.


IPROF

----- PIL integer; default=1; group 23 --- -

IPROF....integer controlling the format of line-printer plots elicited by PATCH(...., PROFIL,....), as follows:

  1. IPROF=0 plots one variable at a time horizontally, with the last 2 arguments of PLOT determining the scale.
  2. IPROF=1 plots all those variables selected by PLOT on the same graph. The abscissa quantity is horizontal.
  3. IPROF=2 prints a table containing values of all the selected variables, "thinned out" in accordance with the values of NXPRIN, NYPRIN or NZPRIN as appropriate.
  4. IPROF=3 prints table and diagram.

For IPROF greater than 0, the third and fourth PLOT arguments have the following significances:

  1. When they differ, and the fourth exceeds the third, they represent respectively the lower and upper limits of the ordinate scale, as for IPROF=0.
  2. When both are equal to zero, the scale limits are taken as the maximum and minimum values of the supplied ordinates.
  3. When both are equal to negative quantities, which are the same as PLOT arguments for other variables at the same PATCH, the ordinate scales will be the overall maximum and minimum for all the variables in question.

The number of columns printed horizontally for option IPROF=0 is set by NCOLPF, whereas for IPROF=1, 2 and 3 the dimensions of the diagrams plotted are determined by ABSIZ and ORSIZ.


IPROP

Index used in GXPRUTIL and elsewhere to indicate which material property is in question.


IPRPSA

--------- PIL integer; group 9 ----------

IPRPSA... is used to carry the PRPS index of the heavier fluid in free-surface problems. See the help and encyclopaedia entries on, Height of liquid and Scalar-equation method GXPRPS, GXHOL, GXSURF and GREX3 for further information.


IPRPSB

--------- PIL integer; group 9 ----------

IPRPSB... is used to carry the PRPS index of the lighter fluid in free-surface problems. Height of liquid and Scalar-equation method

See the help and encyclopaedia entries, and GXPRPS, GXHOL, GXSURF and GREX3 for further information.


IPSA

Method used in PHOENICS to solve the system of algebraic equations for two-phase flows. IPSA stands for Inter-Phase Slip Algorithm.


IROTAA

PIL Integer; group 13 ----------

IROTAA... is a switch used to activate a source term for velocities in cases with rotating coordinate systems.

See the encyclopaedia entry for ROTATIONAL Momentum Sources.


IRUN

---------------------------------------

Ground integer.

IRUN....is the current run number.


ISC

an integer set by EARTH, together with IGR, to dictate which section of GROUND, GREX3, etc is to be entered.

See PHENC: GROUND


ISGx

------ PIL integer; default=0; group 19 --- -

ISG1, ISG2, ISG3, etc were originally provided as spare integer variables which could be ascribed values in (group 19 of) the Q1 file, and then transmitted to the solver module, EARTH, via the eardat file.

They reside in the file which is "included" in both SATELLITE and GROUND Fortran, namely: satgrd.

The common block /ISG/, which is dimensioned in main.htm has 100 elements; but, as will be seen, many of them have other names than ISGx.

These variables have, in the course of time, become PIL variables used for particular purposes, as can be seen by inspecting the common block /ISG/ of satgrd.

Thus ISG20 has been replaced by MAXSEC, which is used in the "time-out" feature.

Further, ISG21 (which has not yet been given a PIL equivalent) sets the minimum number of sweeps which must be performed, regardless of the values to which the residuals have fallen (for versions 3.5.1 and beyond only).

Additionally (for version 3.6 and beyond):


ISKINA

--------- PIL integer; group 13 ---------

ISKINA... is used to carry the number of iterations to be taken in the calculation of the dimensionless skin-friction factor for turbulent wall-functions.

See the help and encyclopaedia entries on TURBUL and WALL, and GXWFUN for further information.


ISKINB

--------- PIL integer; group 13 ---------

ISKINB... is a switch used to activate different formulae for the skin-friction factor for turbulent wall-functions.

See the help and encyclopaedia entries on TURBUL and WALL, and GXWFUN for further information.


ISLN

------- PIL integer array -----------------

Read only.

Internal storage of information set by SOLUTN command.


ISO Dir

(View Menu) ------------------------------------ Photon Help ----

Reset the view direction to (1, 1, 1).


ISOLBK

This sets the iteration frequency with which the user-defined block corrections are performed. The default of 0 means that no block corrections are made. See BLOK for further details.


ISOLX

----- PIL integer; default=-1; group 8 --- -

ISOLX....parameter controlling the iteration frequency of x-wise block-adjustments in the linear equation solver. ISOLY and ISOLZ activate similar adjustments in the y- and z-directions. The adjustments are performed for any variable not solved point-by- point.

The default setting of -1 means that the adjustments will be performed only on the first iteration of each sweep. A setting of -2 would indicate only the first 2 iterations, and so on. A value of zero means that the adjustment is de-activated. This may prove advantageous when the domain is multiply connected due to the presence of blockage barriers.

It is frequently advantageous to set the ISOL parameter for the main flow direction to be > 0, as this can speed convergence. A value of 1 means block-adjustment every iteration, 2 means every second iteration, and so on.

If LITER(phi) is negative, the block-adjustments applied will be displayed at the screen.


ISOLY

----- PIL integer; default=-1; group 8 --- -

ISOLY....see ISOLX


ISOLZ

----- PIL integer; default=-1; group 8 --- -

ISOLZ....see ISOLX


ISTDB1

---- PIL integer; default=1; group 25 --- -

ISTDB1....first time step at which debug printed.


ISTDB2

---- PIL integer; default=1; group 25 --- -

ISTDB2....last time step at which debug printed.


ISTEP

-------------------------------------

Ground integer.

ISTEP....is the time-step number.


ISTPRF

---- PIL integer; default=1; group 23 --- -

ISTPRF....first time step at which fields are printed.


ISTPRL

---- PIL integer; default=10000; group 23 -

ISTPRL....last time step at which fields are printed.


ISWC1

----- PIL integer; default=1; group 15 --- -

ISWC1....first sweep through field for which solution for variables with indices greater than 13 takes place, ie. H1, H2, C1, C2, C3,.....C35.

Economy may be effected by setting this greater than 1, so that the velocity field has time to settle before time is spent on scalar variables.


ISWDB1

---- PIL integer; default=1; group 25 --- -

ISWDB1....first sweep at which debug printed.


ISWDB2

---- PIL integer; default=1; group 25 --- -

ISWDB2....last sweep at which debug printed.


ISWEEP

------------------------------------- Ground integer.

ISWEEP....is the current sweep number.


ISWPRF

---- PIL integer; default=1; group 23 --- -

ISWPRF....first sweep at which fields are printed.


ISWPRL

---- PIL integer; default=10; group 23 -- -

ISWPRL....last sweep at which fields are printed.


ISWR1

----- PIL integer; default=1; group 15 --- -

ISWR1...is the first sweep on which the equations for the volume fractions R1 and R2 are solved. It can sometimes be helpful for convergence to delay the solution of the volume-fraction fields until the sweep at which a reasonable velocity distribution is obtained, for example. See ISWR2.


ISWR2

----- PIL integer; default=10000; group 15 -

ISWR2....is the last sweep on which the volume fractions R1 and R2 are solved. See ISWR1.


ITABL

----- PIL integer; default=3; group 23 --- -

ITABL....controls the tabulation and plotting of spot-values and residuals, the print-out of which is activated by the last two arguments of OUTPUT. The significance of its value is as follows:


ITABL=0....no plots and no tables;
ITABL=1....plots but no tables;
ITABL=2....tables but no plots; and
ITABL=3....tables and plots.


Iteration frequency for user-defined blocks, setting the

(see ISOLBK)


Iteration frequency of x-wise block-adjustments

(see ISOLX)


Iterations

(also see Sweeps)


Iterations, inner, specifying number of

(see LITXC, LITYC, LITZC)


Iterations, maximum number of

(see LITER)


Iterations, termination of

(see ENDIT, LITER and RESREF)


ITHC1

----- PIL integer; default=1; group 15 --- -

ITHC1....is the first outer iteration over slab at which solution for variables with indices greater than 11 takes place, ie. KE, EP, H1, H2, C1, C2, C3, C4, C5, C6, C7, C8, C9, C10. Economy can be effected by setting this greater than 1, so that the velocity field has time to settle before time is spent on scalar variables.


ITHDB1

---- PIL integer; default=1; group 25 --- -

ITHDB1....first hydrodynamic iteration at which debug is printed. This is used in PARABolic calculations.


ITHDB2

---- PIL integer; default=1; group 25 --- -

ITHDB2....last hydrodynamic iteration at which debug is printed. This is used in PARABolic calculations.


ITHYD

-------------------------------------

Ground integer.

ITHYD....is the current iteration number at the current z-slab.

See LITHYD.


ITIMA

---------- PIL integer; group 13 ---------

ITIMA... is used to specify the period in terms of the number of time-steps of a periodic source.

See the help and encyclopaedia entries on ???, and GXTIM for further information.


ITIMB

---------- PIL integer; group 13 ---------

ITIMB... is used to specify the first time-step at which a periodic source should be applied. See the help and encyclopaedia entries on ???, and GXTIM for further information.


ITIMC

---------- PIL integer; group 13 ---------

ITIMC... is used to specify the last time-step at which a periodic source should be applied.

See the help and encyclopaedia entrie on ???, and GXTIM for further information.


IURINI

---- PIL integer; default=0; group 11 --- -

IURINI....is used to initialize the U1 velocity in a cylindrical polar coordinate system, to represent:

  1. a constant u field, ie. U=constant (IURINI=0, the default)
  2. Solid body rotation (constant angular velocity), ie. U/radius = constant (IURINI=-1).
  3. free vortex flow (constant angular momentum), ie. U*radius = constant (IURINI=1); and

FIINIT(U1) and FIINIT(U2) are set to one of the above constants, and this results in EARTH initializing the velocity fields to contant/radius or constant*radius according to IURINI = 1 or -1.

See also IURVAL and IURPRN.


IURPRN

---- PIL integer; default=0; group 21 --- -

IURPRN....provides options for the print-out of the velocity U1 and U2 in cylindrical-polar coordinates ( CARTES=F ). These options are:

  1. IURPRN=0 (the default) causes the u fields themselves to be printed.
  2. IURPRN=-1 causes the u fields printed to be divided by the radial distance of u from the axis, ie. U/radius (angular velocity) is printed. EARTH sets NAME(3)=U1/R and NAME(4)=U2/R. For a solid-body rotation flow, IURPRN=-1 would result in U1 equal to the angular rotation rate everywhere.
  3. IURPRN=1 causes the u fields printed to be multiplied by the radial distance of u from the axis, ie. U*radius (angular momentum) is printed. EARTH sets NAME(3)=U1*R and NAME(4)=U2*R.

See IURINI and IRVAL for further information.


IURVAL

---- PIL integer; default=0; group 13 --- -

When U1 or U2 are solved for, and CARTES=F, the 'value' argument of COVAL, INIT, PLOT and WALL is interpreted by EARTH as

Un * RADIUS ** IURVAL

The argument is thus:

Un, i.e. velocity, when IURVAL has its default value;
Un / RADIUS, i.e. angular velocity, when IURVAL = -1; or
Un * RADIUS, i.e. angular momentum, when IURVAL = 1

It is especially useful when the boundary conditions are of solid- body rotations ( IURVAL = -1 ) or constant angular momentum ( IURVAL = 1 ).

The value of IURVAL affects all patches. If the angular-velocity or angular momentum interpretation is to be applied only to selected patches, IURVAL should be left at its default value, and the patch names should have UMR or UDR as the 6th, 7th and 8th characters, according to whether U multiplied by R or U divided by R is required.

For example, the commands,
PATCH(ROTATUDR,LOW,1,NX,1,NY/2,1,1,1,1)
COVAL(ROTATUDR,P1,FIXFLU,1.0)
COVAL(ROTATUDR,U1,ONLYMS,20.0)
set a mass inflow of 1 kg/s rotating as a solid body at 20 radians per second at the inner half of the boundary at IZ=1.

The commands,
PATCH(SWIRLUMR,LOW,1,NX,NY/2+1,NY,1,1,1,1)
COVAL(SWIRLUMR,P1,FIXFLU,2.0)
COVAL(SWIRLUMR,U1,ONLYMS,10.0)
set a mass inflow of 2 kg/s rotating with a constant angular momentum of 10 ( m**2/s ) at the outer half of the boundary at IZ=1.

See IURINI and IURPRN for further information.


IVARBK

-------- PIL integer; default=0; group 7 -

This identifies the variable selected for user-defined block corrections, eg IVARBK=14 would select the 1st phase enthalpy for additional block-corrections. The index number associated with each variable can be found in the NAME entry. IVARBK=-1 selects all solved-for variables.

See BLOK for further details.


IVRMCO

Integer used in GXVIRMS to denote virtual-mass coefficient.


IX

-----------------------------------------

Integer; default=1.

IX....ranges from 1 to NX, denoting the grid-point location in the x-direction of PHOENICS, but not necessarily in the cartesian-x direction for BFC=T. In the latter IX=I-1 (see BODY-F for the indicial nomenclature in use in body-fitted coordinates).


IXF

(Grid, Contour, Vector and Stream Menu)---------------------------------------- -

Ground integer.

IXF....is the west extent of the current patch within the slab.


IXF

(Grid, Contour, Vector and Stream Menu)---------------------------------------- Photon Help ----

[IXF] is the lower limit of the current block region in X direction.


IXL

(Grid, Contour, Vector and Stream Menu)---------------------------------------- -

Ground integer.

IXL....is the east extent of the current patch within the slab.


IXL

(Grid, Contour, Vector and Stream Menu)---------------------------------------- Photon Help ----

[IXL] is the upper limit of the current block region in X direction.


IXMON

----- PIL integer; default=1; group 22 --- -

IXMON....IX-value of spot-value location.

The print-out of fields of variables is bulky: it is best therefore activated infrequently.

However, EARTH can also provide compact print-out, which can be activated every sweep or every few sweeps; this allows the user to monitor the progress of the iterative solution.

This monitor print-out comprises the values of all variables for which Y has been entered in the sixth argument of OUTPUT, for a single grid location identified by the indices IXMON, IYMON and IZMON.

The choice of spot-value location is thus at the user's discretion; values of IXMON, IYMON and IZMON would generally be chosen to lie within a region of the flow which is of particular interest, either from the engineering standpoint, or because convergence difficulties are expected in that region.


IXPRF

----- PIL integer; default=1; group 23 ---

IXPRF....is the first IX column printed in the tabulation of the fields selected by OUTPUT.


IXPRL

----- PIL integer; default=10000; group 23 -

IXPRL....is the last IX column printed in the tabulation of the fields selected by OUTPUT.


IY

-----------------------------------------

Integer; default=1.

IY....ranges from 1 to NY, denoting the grid-point location in the y-direction of PHOENICS, but not necessarily in the cartesian-y direction for BFC=T. In the latter IY=J-1 (see BODY-F for the indicial nomenclature in use in body-fitted coordinates).


IYF

(Grid, Contour, Vector and Stream Menu)----------------------------------------

Ground integer.

IYF....is the south extent of the current patch within the slab.


IYF

(Grid, Contour, Vector and Stream Menu)---------------------------------------- Photon Help ----

[IYF] is the lower limit of the current block region in Y direction.


IYL

(Grid, Contour, Vector and Stream Menu)---------------------------------------- -

Ground integer.

IYL....is the north extent of the current patch within the slab.


IYL

(Grid, Contour, Vector and Stream Menu)---------------------------------------- Photon Help ----

[IYL] is the upper limit of the current block region in Y direction.


IYMON

----- PIL integer; default=1; group 22 --- -

IYMON....IY-value of spot-value location. See IXMON.


IYPRF

----- PIL integer; default=1; group 23 --- -

IYPRF....is the first IY column printed in the tabulation of the fields selected by OUTPUT.


IYPRL

----- PIL integer; default=10000; group 23 -

IYPRL....is the last IY column printed in the tabulation of the fields selected by OUTPUT.


IZ

-----------------------------------------

Integer; default=1.

IZ....ranges from 1 to NZ, denoting the grid-point location in the z-direction of PHOENICS, but not necessarily in the cartesian-z direction for BFC=T. In the latter IZ=K-1 (see BODY-F for the indicial nomenclature in use in body-fitted coordinates).


IZDB1

----- PIL integer; default=1; group 25 --- -

IZDB1....first IZ slab at which debug printed.


IZDB2

----- PIL integer; default=1; group 25 --- -

IZDB2....last IZ slab at which debug printed.


IZF

(Grid, Contour, Vector and Stream Menu)---------------------------------------- Photon Help ----

[IZF] is the lower limit of the current block region in Z direction.


IZL

(Grid, Contour, Vector and Stream Menu)---------------------------------------- Photon Help ----

[IZL] is the lower limit of the current block region in Z direction.


IZMON

----- PIL integer; default=1; group 22 ---

....IZ-value of spot-value location. See IXMON.

For PARAB = T, the graphical monitor is activated only for IZ values which are whole-number multiples of IZMON

Negative values of IZMON may also be accepted, These have the effect of replacing the displays of "spot values" and residuals on the graphical-monitor screen by those of the whole-domain maximum and minimum values of each variable.

The spot values printed in the result file remain those pertaining to the IZ-slab corresponding to the absolute (ie sign-free) value of IZMON.


IZPRF

----- PIL integer; default=1; group 23 --- -

IZPRF....is the first IZ column printed in the tabulation of the fields selected by OUTPUT.


IZPRL

----- PIL integer; default=10000; group 23 -

IZPRL....is the last IZ column printed in the tabulation of the fields selected by OUTPUT.


IZSTEP

------------------------------------- Ground integer.

IZSTEP....is the current z-slab.


IZW1

------ PIL integer; default=0; group 19 --- -

IZW1....is the iz location of the last slab in part one of an n-part moving grid. See ZMOVE, and the piston-in-cylinder example in subroutine GXPISTON called from section 1 of group 19 of GREX.

See also AZW1, BZW1 and CZW1.


wbs