Encyclopaedia Index


----------------------------------------- Integer flag; value=14.

H1....standard name used to denote first-phase enthalpy.

H1 may, for fluids of uniform specific heat, be used to represent first-phase temperature, in which case it may be convenient to rename it, for example thus:

NAME(14) = TEMP, or

See PHI and NAME for further information.


----------------------------------------- Integer flag; value=15.

H2....standard name used to denote second-phase enthalpy.

See:- H1, PHI and NAME for further information.


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

A selection of available plotting devices are listed in a subsequent sub-menu. By clicking on any of them screen plotting will be saved on that device.

In the case of an off-line device, a file name will be required. PHOTON will prompt for the input of the file name. The CANCEL button will bring the system one menu level up without taking any further action.


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

HA[tch]....sets up or changes the grid-hatching parameters. It will prompt for hatching directions, which may be any or all of X, Y and Z, and hatch spacing for each direction, which is specified as a fraction of the grid length in that direction.

See also : GRID HATCH


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

[Hatch] activates grid-hatching in BFC cases. Hatch spacing and direction can be specified in the GRID editor.


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

[HatchDir] specifies the hatch direction. It can be X, Y or Z.


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

[HatchDis] specifies the hatch spacing as a fraction of the grid. It is specified as a fraction of the grid length in that direction.


Hazard assessment via CFD

To see a document outlining the principles and indicating how PHOENICS can best be used for the purpose, click here.


---- PIL real flag; value= -10240.0; grou -

HEATBL....is the flag to which CMDOT should be set, in GROUP 10, if the mass-transfer rate from one phase to the other phase is to be computed from a heat balance. HEATBL has a pre-set value, -10240.0, which should not be changed.

See also CMDOT and PHINT.

Height-of-liquid method (H-O-L)


Flow simulations of real processes often involve fluids that are separated by a sharp interface. Mould filling, film coating, wave formation, liquid sloshing in tanks are some examples.

The calculation of the interface is usually a computer-intensive task, and yet a necessary step in the solution procedure and often the main output from the computation. PHOENICS offers several ways of tracking such an interface, such as DONACC (in two-phase mode) or the scalar-equation method (see PHENC entry SEM).

An addition, PHOENICS allows the economical tracking of the interface when it is known beforehand that the surface does not exhibit overturning. The method, called Height-Of-Liquid (HOL), calculates the height of the interface at each point by focussing on one of the fluids (say the lower one) and computing the height of the liquid column through a mass balance over the sides of the column.

HOL works computationally as a single-phase method, and it can be used in all three coordinate systems and for transient and steady-state problems.

HOL is attached to PHOENICS as a GROUND station and delivered in source code. It forms a part of the advanced multi-phase option. The activation of the HOL features is from PIL or from PHOENICS-VR.

Details of how to activate HOL are provided in the HOL-method lecture which appears in the multi-phase section of the general lectures on PHOENICS.


----------- PIL real; group 13 -----------

HGSOA... is a constant 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 as an iteration convergence criterion. See the help on GRAV for further information.


------------ PIL real; group 13 ----------

HGSOB... is used to specify the difference in densities between the first- and second-phase fluids in a two-phase pipe-flow case for which a lateral gravitational acceleration of the fluid is required. See the help and encyclopaedia entries on GRAV, and GXLATG for further information.


------ PIL real flag; value=6.0; group 13 - -

HIGH....is a PATCH type used for setting sources per unit high ( ie. larger-z ) area by way of COVAL in group 13.


See PHENC entry: SCHEMES for convection discretization


----------- PIL logical Switch ----------

HIGHLO... when set to true, activates checks to ensure that corrections to the dependent variables lie within the limits defined using the variables VARMIN and VARMAX.


------ acronym for higher-order convection schemes

See PHENC entry: SCHEMES for convection discretization


------- PIL logical; default=F; group 19 --- -

Set HOL=T to activate the height-of-liquid method for calculating flows with interfluid boundaries.

See PHENC entry: height-of-liquid.


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

HPOR.... indicates which whole-field store will be used for the porosity of the high face in response to the command STORE(HPOR). Once stored, this field should be initialized in group 11. The field values are set to 1.0 by default.


----- PIL real; default= 1.0; group 8 --- -

HUNIT....A multiplying factor for the built-in enthalpy source terms, which are assumed to be in SI units (ie J/kg). If the enthalpy equations (H1 and H2) are being solved in another unit system, HUNIT should be set to the conversion factor between the current unit system and SI. Thus if H1 is being solved as a temperature equation, HUNIT should be set to 1./Cp, where Cp is the specific heat. As a further example, for steam-water simulations it can be convenient to have the units of enthalpy defined as 1.0E5 J/kg. In such a case, HUNIT would be set to 1.E-5.


----- PIL real flag; value= 21.0; group 13 -

HWALL...is a PATCH type used in group 13 in conjunction with COVAL for representing the sources resulting from a wall at the high faces of the cells identified by PATCH. See WALL and WALLS for further information


The parameter DIFCUT permits selection of either the upwind scheme (DIFCUT=0.0) or the hybrid upwind scheme (DIFCUT=0.5). The latter is the default.

In the upwind scheme, the diffusive flux is present irrespective of the cell Peclet number; whereas in the hybrid scheme the diffusive flux is cut out for Peclet numbers in excess of 2.0(1.0/DIFCUT).

See the Encyclopaedia entry 'DIFCUT' for further details.

Hydrodynamic iterations of slabs

(see LITHYD)