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kathiravan July 12, 2006 00:44

how to converge the solution for fine mesh
 
hi experts i am doing one problem related to heat transfer in star cd. my prob is one heated cylinder is placed inside a square cavity. now i want to find out heat transfer coefficient around the cylinder. for coarsh mesh the solver converges very quickly. but for fine mesh it will not converges. for using SIMPLE algorithm it will diverges immeadialy. but my boundry condition everything same for coarsh and fine mesh. so how to attack this problem from very fine mesh. after that can you tell me how to plot graph for theta verses heat transfer coefficient.


Zamir Rashid July 12, 2006 04:20

Re: how to converge the solution for fine mesh
 
Try using under relaxation factors for the solved parameters.

DenizeN July 12, 2006 07:04

Re: how to converge the solution for fine mesh
 
Try to read about y+ and turbulence models in user guide.

kathir July 20, 2006 00:06

Re: how to converge the solution for fine mesh
 
i am using only laminar flow

DenizeN July 20, 2006 02:37

Re: how to converge the solution for fine mesh
 
then your flow have complex structure, use transient or pseudo-transient solver. With coarse mesh you smooth flow structure and solution converged (real structure of your flow is more comlicated).

kathir August 11, 2006 01:30

Re: how to converge the solution for fine mesh
 
hi DenizeN

thanks for responce. in my problem i activate to print the parameter values( temp, velocity etc) of each cell. at the time the result shows the negatve temp values. how is it possible. because my air temp is 25 c and fin base temp is 100 c. but it shows surrounding air temp is less than 0. but in contour plot it not shows the negative values. but print values shows the negative values. please give me what is the mistake in my approach thank you sir


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