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Parshant Dhand April 28, 2003 15:22

Courant Number
 
HI there, i am modeling turbulent flow in a cylinder, my problem is that while solving the solution converges if i reduce the courant number to say 0.001, but this does not predict the actual physical flow, however the solution does not converge for courant number 0.1, but this flow is similar to actually physical phenomena, can anybody please explain, how to choose optimum courant number value and any other means by which i can achieve convergence.

Alex Munoz April 29, 2003 20:39

Re: Courant Number
 
Hi

I apologize for delaying my response until someone else with better understanding reply. However, It seems that nobody wants to lead you question. Therefore allow me to try without having total accuracy of my answer.

Courant number defined as the time for a fluid move only a fraction of the grid spacing Äx in a time step (Pope S.B. 2000)

k^0.5*del time/del space= 1/20

where k is the turbulent kinetic energy del time is the delta of time de space is the delta of space and 1/20 is the courant number

As a result, when you decrease the courant number you indirectly decrease the del time. In this way, the system is able to capture the periodicity of the flow field.

I hope this answer helps you

Alex Munoz


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