Page 332 - Introduction to Computational Fluid Dynamics

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APPENDIX C. 2D CARTESIAN CODE
by harmonic mean. Similarly, care is exercised in evaluation of periodic boundary 11:59
coefficients in the pressure-correction equation.
Subroutine SORCE This routine includes standard source terms for all variables.
Thus, for u and v velocities, pressure-gradient terms are included but body force
terms are excluded. In the turbulent kinetic energy source term, the near-wall bound-
ary node is excluded as required for implementation of the high Reynolds number
(HRE) turbulence model (see Chapter 5). For the LRE model, the USER will have
to modify entries in BOUND and SORCE routines. For temperature, the standard
source term is set to zero. To include effects of viscous dissipation or heat genera-
tion due to chemical reaction or radiation, the ADSORB routine in the USER file
must be used.

Subroutine APCOF In this routine the coefficient of P is assembled by adding
SP (I , J) and dividing by α. The APU and APV coefficients store the AP coefficient

of the two momentum equations whereas AP1 stores the coefficient of p .
P
Subroutine PROPS Here, density, specific heat, and viscosity variables are spec-
ified. If BSOR (8) is .TRUE. then the default specifications can be overwritten in
the ADSORB routine in the USER2D.FOR file.
Subroutine UNST In this routine, Su and Sp are appropriately updated for truly
unsteady or false-transient calculation.

Subroutine UPDATE In this routine, all new time values are set in old time
values.

Subroutine INFLUX In this routine values of ˙ m at inlet boundaries are evaluated
for all variables to form the RNORM array. The latter is used to normalise the
residual calculation in subroutine SOLVE.
SubroutineMASBAL Thisroutinecalculatesthedomainexitmassflowratebased
on specifications of velocity boundary conditions in subroutine BOUND. However,
this mass flow rate must be the same as the sum of all mass flow rates specified at
the inlet boundaries. During an iterative solution, this balance is rarely maintained.
Therefore, before solving the pressure-correction equation, the prevailing exit-plane
velocities are uniformly corrected in this routine by the ratio of inlet to exit mass
flow rates.
Subroutine PVCOR In this routine, the mass-conserving pressure-correction p
m
is first recovered and then pressure and velocities are corrected. The smoothing
pressure-correction p is stored for printing when desired. The routine also cal-
sm
culates the mass residual R m , as explained in Chapter 5.
Subroutine BOUNDP In this routine, boundary pressures are extrapolated from
near-boundary values as explained in Chapter 5. Note that p values are also
m
extrapolated to effect correct velocity corrections at the near-boundary nodes in
routine PVCOR. Further, care is exercised to effect correct interpolation of pressure