Page 330 - Introduction to Computational Fluid Dynamics

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APPENDIX C. 2D CARTESIAN CODE
Variable Meaning May 25, 2005 11:59
UNSTDY Logical – refers to unsteady-state calculation
UO Array containing u 1 velocity at old time
UPWIND Logical – refers to upwind difference scheme
V Array containing u 2 velocity
2
VISCOS Reference viscosity (N-s/m )
VIS Array containing laminar viscosity
VIST Array containing turbulent viscosity
VO Array containing u 2 velocity at old time
3
VOL Array containing cell volume (m )
W Array containing u 3 velocity
WO Array containing u 3 velocity at old time
X Coordinate of node I (m)
XC Coordinate of cell face at w
Y Coordinate of node J (m)
YC Coordinate of cell face at s

user may introduce additional problem-dependent indices such as IB1, IB2, etc. The
grid coordinate data may be normalised or real.
Subroutine TITLE In this routine, the problem-specific title is inserted.

Subroutine INIT In this routine, the best known initial guesses for all relevant
variables are given. Also, known INFLOW conditions are specified.

Subroutine BSPEC Here, boundary types are specified. Identifiers for boundary
type and boundary condition are declared by logical variables such as WEST or
SYMM. WALLT and WALLQ stand for, respectively, temperature and heat influx
specified at wall boundaries. EXIT1 and EXIT2 stand for exit boundary conditions.
When EXIT1, the first normal derivative at the boundary is set to zero, for EXIT2,
the second normal derivative is zero. BLOCK identifies blocked regions of the
domain. These specifications must be made carefully and a hand sketch of the
domain will assist correct specifications. Also, reference may be made to the node-
tagging section in Chapter 5.
Subroutine ADSORB This routine is used to add any special source terms for
each variable solved. The standard source terms are included in the SORCE routine
in LIB2D.FOR file. The routine is also used to overwrite USER-defined specifica-
tions for density, specific heat, and viscosity. The routine is also used to specify
a fixed-pressure boundary condition. Further, the routine is used to give periodic
boundary conditions.
Subroutine RESULT In this routine, the final converged solutions are printed. The
routine is also used to extract useful parameters such as friction factor or Nusselt
number from the converged solution. This routine is also used to create output files
for contour and vector plots using graphics packages such as TECPLOT.