# 2D Heat Convection Guide by guy21

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```									                                   2D Heat Convection Guide

Perumal Nithiarasu, Civil and Computational Engineering Centre, School of
Engineering, University of Wales Swansea, Swansea SA2 8PP, UK,
e-mail any mistakes to: P.Nithiarasu@swansea.ac.uk

The source code for heat convection directly       second line are not used. The last one is used
uses the output files from the mesh generator.     and should be a small positive number close to
Two extra input files are necessary. They are      zero (initial pressure value). The third line
‘bc.bco’ and ‘par.dat’.       The file bc.dat      gives the number of time steps, total time (not
contains information relevant to the boundary      used), time step option (-1 for fixed time step),
conditions. For a simple problem of natural        after every ‘iwrite’ time steps information will
convection in square cavity boundary               be written on the screen, time step value.
conditions are ( bc.dat )
Fourth line is the safety factor (applicable only
no boundary segements                              for local time stepping). Fifth lines are theta1
4                                                  and theta2 values and they should be
sec. no. and bc. code                              remaining unity for a semi-implicit form.
1 500
2 502                                              The sixth line reads Reynolds number, Prandtl
3 500                                              number, Rayleigh number and Richardson
4 501                                              number. The seventh line reads the initial
values for temperature, u velocity and v
The above input file is for natural convection     velocity. The last line reads the information
in a square cavity (Figure 7.26 in the book).      about whether the problem is natural
The code 500 at the bottom side represents the     convection or not. The code ‘isnat’ equal 1
no-flux condition for the temperature equation     represents natural convection problem. Any
and no-slip for velocities. The codes 501 and      other code represents either mixed or forced
502 represent the constant temperatures on the     convection. For mixed convection Richardson
vertical walls (501, T = 1 and 502, T = 0). The    number is non-zero. For forced convection
second input file ‘par.dat’ for natural            Richardson number is zero.
convection is
solver option iconj = 1, conjugate gradient        within the fortran code.
1
roinf vxinf vyinf pinf
0.10000E+01,0.10000E+01,         0.00000E+00
0.10000E+00
ntime timt ilots iwrite dtfix
50 0.0 -1 50 0.10000E-04
safety factor
0.100000
0.1000E+01 0.1000E+01
0.100000E+03 , 0.710000E+00,1000.0 , 1.0
temperature,velocity initial conditions
0.0 0.0 0.0
nat. convec., isnat = 1, and node nuber to
prescribe pressure
1 1

Two solvers are available if iconj = 1, the
conjugate gradient solver is used and any other
number a banded Gausian elimination solver is
used. For the latter option the bandwidth in the
file ‘inpu.dat’ should be correct if some other
mesh generator is used. The mesh generator
provided      automatically     calculates   the
bandwidth. The first three entries of the

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