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david April 30, 2008 05:52

time step calculation

i am doing an unsteady simulation here in the iteration panel what is the value we need to give in TIME STEP SIZE and also in NUMBER OF TIME STEPS....

The case which i am dealing with is a single shell and tube heat exchanger , where the velocity of fluid in tube varies with time .....

how the time step is calculated.... thx in advance

Ramesh. K May 7, 2008 01:36

Re: time step calculation
time step is calculated with the help of cfl number. if u know the minimum grid size and the velocity of the fluid or guess of the fluid velocity u can find the time step by a*delt/delx <= 1 with this u can either have local time stepping or golbal time stepping according to the problem

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