Encyclopaedia Index

GALA GCLEAR GCV (General Colocated Velocities GDOM GDRAW GENIE GENK GENMIX GENTRA

GEOMETRY (creation for VR) GEOMETRY (in PHOTON)
GETCOV GGET GGRID GLINE GLIST GOTO GPATCH GPHERR GPROJ

GRAPHICS PRIMITIVES GRAVITATIONAL_BODY_FORCES GRDCHK GRDPWR GREAT GREX3.F/GREX GRID GRID Generation in PIL GRND GROUND GROUP GRSP1

GSET GT-NAME GTEXT GTPARG GVIEW GXFILES GXMAKE GXMONI


GALA

------ Logical; default=F; group 8 ---- -

When GALA is set to T, the pressure-correction equation is driven by residuals derived directly from the volume flow rates. This can be highly beneficial when the substantial derivative of density is zero, as it is at material discontinuities of incompressible fluids.

GALA can be used in the modelling of the movement of a water wave, for at the water-air interface the substantial derivative of density is zero. Supplementary FORTRAN coding is required in GROUND that tracks the location of the interface and sets the density field to accord with it.

If volume sources exist ( ie the substantial derivative of density is non-zero ), eg at flame fronts, or because of changes of porosity, appropriate coding must be supplied by the user in Section 7 of Group 8 of GROUND.


GCLEAR

----------- PIL Graphics command ---- -

The syntax is : GCLEAR

This clears the graphics stack, and allows a new picture to be built.


GDOM

------------- PIL Graphics command ---- -

The syntax is : GDOM(I1,I2,J1,J2,K1,K2,ICOL,IDASH)

This draws a domain outline over the limits set in colour ICOL and dash type IDASH.


GDRAW

------------ PIL Graphics command ---- -

The syntax is : GDRAW

This draws the current picture - Note that the results of any PIL graphics commands (except VIEW) are not drawn on the screen until a GDRAW command has been received.

Inside the MENU environment, GDRAW can put the picture in various windows:
GDRAW puts the current picture in the full screen window
GDRAW(MONITOR) puts the current picture in the monitor window
GDRAW(NOTICE) puts the current picture in the notice window
GDRAW(LOGO) puts the current picture in the CHAM logo window.

GDRAW(NOTICE) and GDRAW(LOGO) are for two-dimensional drawings: they draw only PTEXT and PLINE, and ignore GTEXT and GLINE etc.


GENK

------ Logical; default=F; group 19 --- -

GENK....= T activates the inclusion of all spatial derivatives of velocity in the generation function in subroutine GXSQUR called from GXGENK called from GREX. See DUDX for related information. In BFC cases, subroutine GXGENB is called to compute the full generation term instead of GXSQUR.


GETCOV

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

The syntax is : GETCOV(NAME,PHI,CO,VAL)

GETCOV returns the COefficient and VALue for the variable PHI in the patch NAME. CO and VAL can be any valid PIL real variables.See also PATCH and COVAL.


GETOUT

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

The syntax is : GETOUT(PHI,CT1,CT2,CT3,CT4,CT5,CT6)

GETOUT returns the arguments of OUTPUT for variable PHI into 6 valid PIL character variables or elements of character arrays. Values are returned as Y or N.


GETPTC

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

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

GETPTC returns the type and limits of patch name NAME. TYPE can be any valid PIL real and the limits can be any valid PIL integers.


GETSOL

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

The syntax is : GETSOL(PHI,CT1,CT2,CT3,CT4,CT5,CT6)

GETSOL returns the arguments of SOLUTN for variable PHI into 6 valid PIL character variables or elements of character arrays. Values are returned as Y or N.


GGRID

------------ PIL Graphics command ---- -

The syntax is : GGRID(PLANE,IP,L1,L2,L3,L4,ICOL,IDASH)

This draws a section of grid on the selected plane in colour ICOL and dash type IDASH. The PLANE can be X, Y or Z. IP is the plane number, and the in-plane limits L1-L4 are;

for plane X - J1,J1,K1,K2
Y - I1,I2,K1,K2
Z - I1,I2,J1,J2

If the colour index ICOL is less than or equal to zero, it has the following functions:
ICOL = 0 draws outlines and region boundaries in different colours;
ICOL = -1 highlights the current region in the X direction;
ICOL = -2 highlights the current region in the Y direction;
ICOL = -3 highlights the current region in the Z direction;
ICOL = -4 draws region boundaries only.

If IDASH is greater than or equal to 10, the dash type will be IDASH-10 and labels will be shown on regions.


GLINE

------------ PIL Graphics command ---- -

The syntax is : GLINE(I1,J1,K1,I2,J2,K2,ICOL,IDASH)

GLINE draws a grid line between the points (I1,J1,K1) and (I2,J2,K2) in colour ICOL and dash type IDASH.


GLIST

-------------- Command --------------- -

GLIST....Command to list grid-generation elements.

Options are: GLIST(P) List all points
GLIST(L) List all lines
GLIST(F) List all frames

See GSET for instructions on how to create points, lines and frames.


GOTO

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

The syntax of this construct is as follows:

GOTO label1 . . LABEL label1

Restrictions are:

  1. Jumping into nested structures is forbidden, although jumping out is allowed.
  2. There must be no space between the GO and the TO.
  3. The LABEL character string may be up to 68 characters long.

GPATCH

----------- PIL Graphics command ---- -

The syntax is : GPATCH(NAME,ICOL,IDASH[,GRID])

This draws the outline of the named patch in colour ICOL and dash type IDASH. If the patch name is ALL, then all patches will be drawn. By default patches are drawn in outline, but the optional parameter GRID causes the grid on the patch surface to be drawn as well.

If the NAME is prefixed by an asterisk '*', the patch name will not appear.


GPHERR

----- Integer; Default=0 ------------ -

Read only.

Satellite only, error flag for PIL graphic operations.


GPROJ

------------ PIL Graphics command ---- -

GPROJ....Command to draw the projection of a PATCH on a specified grid plane.

Format: GPROJ(Patch_name, dir, ipl, icol, idash)

arguments: dir X, Y or Z, ipl the number of the X, Y or Z plane on which the projection is made, icol the colour index, itype the line type index (0 for solid line, 1 and upwards for dashed lines).

Note that the patch name is not displayed with the projection.


GRDCHK

---- Command; group 6 --------------- -

The syntax is : GRDCHK(PLANE,LOC1[,LOC2][,NOPLOT])

This command performs a BFC-grid orthogonality check on an I,J or K plane, as specified by PLANE. LOC1 is the number of the first plane to be checked, and LOC2 is an optional parameter showing the last plane to be checked. Thus :

GRDCHK(I,1) - checks I plane 1; and
GRDCHK(K,3,NZ-1) - checks K planes 3 through to NZ-1

For each plane specified, the minimum angle in each cell is calculated, and displayed by colouring the cells in the range from blue to red, where red denotes 90 degrees, and blue 0 degrees. The optional last parameter NOPLOT disables the graphical display.

The angle calculated is 90 minus the angle between a line joining adjacent cell centres, and the normal to the cell-face separating them. This is done for each of the four faces on the plane, and the smallest angle is chosen. Fully orthogonal cells will have angles of 90 degrees. If any cells have angles below ANGMIN, their indices are displayed.

See ANGMIN for details.


GREAT

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

Real flag; value=1.0E20.

GREAT....A large number, used in EARTH. Do not re-set. The default value may be re-set during installation to suit the precision of the computer.


GRSP1

GRSP1 is an integer index, usable in subroutines called from GROUND, for accessing the 2D array of values, pertaining to the current IZ-slab, of: values of anything the user determines. In order to provide storage for the array indexed by GRSP1, subroutine MAKE must be called from Group 1, section 1 of GROUND. Similar indices are GRSP2, GRSP3, ... , GRSP10. These indices are reserved for use in GROUND and are guaranteed not to be used in any way in GREX or the GX suite.


GT-NAME

When the character > is the first character of a patch name, and the second, third, fourth and fifth characters are the name of a stored (or solved) variable, a source is created which is equal to:

CO * (VAL * S - PHI) where S is the local value of the above-mentioned stored variable and PHI is the local value of the variable to which the source is applied.

For example, the following statements in a Q1 file:

PATCH(>W1,CELL,NY/4+1,NY/2,NZ/4+1,NZ/2,1,LSTEP)
COVAL(>W1,V1,1.0E3,-1.0)

will provide a source of V1 which equals 1.0E3*(- W1 - V1) .

This will tend to make V1 equal to - W1 .


GTEXT

------------ PIL Graphics command ---- -

The syntax is : GTEXT(TEXT,I1,J1,K1,ICOL)

GTEXT writes the specified TEXT characters at the specified position (I1,J1,K1) in colour ICOL.


GTPARG

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

GTPARG Command used to get the parameters of existing PATCHes and COVALs

Options are:

GTPARG(patch_name, N, ct1, it1, ct2, it2) This command:-

sets ct1=N if the patch does not exist, and no values are returned to it1,ct2,it2, sets ct1=Y if the patch exists, returns the patch number to it1, returns the patch type to ct2 in character form, returns zero to it2 (ie not used at present).

GTPARG(patch_name, X, ct1, it1, ct2, it2)

returns to ct1 and ct2 the symbols #, $ or % to signify that region numbers have been used for setting the X limits, returns to it1 and it2 the region (or cell) numbers, ct1 or ct2 will be blank if no symbols were used (ie X limits are cell numbers). The string :ct1::it1:,:ct2::it2: will therefore reconstruct the original setting of X limits for the patch.

GTPARG(patch_name, Y, ct1, it1, ct2, it2) returns to ct1, it1, ct2, it2 the symbols and numbers used for the Y limits of the patch.

GTPARG(patch_name, Z, ct1, it1, ct2, it2) returns to ct1, it1, ct2, it2 the symbols and numbers used for the Z limits of the patch.

GTPARG(patch_name, T, ct1, it1, ct2, it2) returns to ct1, it1, ct2, it2 the symbols and numbers used for the T (time) limits of the patch.

GTPARG(patch_name, C, variable_name, ct1, ct2) This use of GTPARG will return the COVAL arguments to ct1 (coefficient) and to ct2 (value) for the specified patch and variable name.

In the commands above, ct1 and ct2 are any user-declared PIL character variables, it1 and it2 are any user-declared PIL integer variables.


GVIEW

------------ PIL Graphics command ---- -

The syntax is : GVIEW(i) where i is X, Y, Z or P

This sets the view direction either to one of the X,Y, or Z directions, or to a perspective view, with view direction (1,1,1) and up direction (0,1,0).

Alternatively : GVIEW(P,I,J,K)

sets the view direction to I,J,K (as in PHOTON). Clashes between view and up directions are resolved internally.

Alternatively : GVIEW(UP,I,J,K)

sets the up direction to I,J,K.

The VR-Editor may also write the following GVIEW commands to Q1, if the relevant settings have been changed from the default values:

Note that only the VR-Editor can write a Q1 file, so changes made in VR-Viewer will not be captured unless the Editor is re-entered and the Q1 saved.


GXMAKE

GXMAKE is a subroutine which may be called in Ground coding, GROUP sections 1 or 3, in order to create storage for variables required by the user.

For details, see PHENC entry FUNCTION ...


GXMONI

Three kinds of monitoring information can be displayed, selected by the setting of ISG50 in Q1 (or in the Editor from Options, Solver Monitor Options or Main Menu, Output, Monitor graph style). The options are:

ISG50 = 0 : display the spot (probe) values on the left, and normalised residuals on the right;

ISG50 = 1 : display maximum value in the field on the left and minimum value on the right; and

ISG50 = 2 : display maximum correction on the left and net sum of sources on the right.

The display can be switched at run-time by interrupting the run and clicking the 'Monitor' box.

By default, the monitor window will start showing 10 sweeps. At 11 sweeps it will rescale to show 100, and at 101 it will rescale to show all sweeps. If the number of sweeps (LSWEEP) is very large, it can be very hard to see the convergence behaviour especially early in the run. The Q1 setting:
SPEDAT(SET,GXMONI,SWEEPWIDTH,I,nsweep)
will cause the monitor window to show the last N sweeps on a rolling basis. This can also be switched from Editor, Options, Solver Monitor Options.

At the end of the Earth Solver run a snapshot of the final convergence monitor screen is saved to the file gxmoni, in the current working directory. This allows the convergence behaviour to be seen at a later time. The snapshot is of whateve monitor display is active at the end of the run.

If all three monitor plots are required, the Q1 setting :
SPEDAT(SET,GXMONI,PLOTALL,L,T)
will cause all three images to be saved as gxmoni_spot, gxmoni_mnmx and gxmoni_mxc. This can also be activated from Editor, Options, Solver Monitor Options.

In a transient case, such files are created at each time step for which the flow fields are dumped, as controlled by the integers IDISPA, IDISPB and IDISPC. In this case the filenames are gxmoni1, gxmoni2 etc.

If these files are not required, their creation can be inhibited by adding to the Q1 file the line:
SPEDAT(SET,GXMONI,TRANSIENT,L,F)

The file type for the gxmoni file is set in CHAM.INI in the [Graphics] section as PlotType. The default setting is gif. The alternative settings are jpg, bmp or pcx.