# time dependent problem

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 October 9, 2008, 13:55 time dependent problem #1 Adrian Guest   Posts: n/a hi all Im still working with cars Im trying to do depedent time calculations and I dont know which values do I have to put in Time step size (s) Number of time step and max. Iterations per time step to begin this test thank so much if anybody can help me greetings to you all

 October 9, 2008, 15:48 Re: time dependent problem #2 Paul Guest   Posts: n/a What kind of time calculations do you mean?

 October 10, 2008, 06:32 Re: time dependent problem #3 Prasad Guest   Posts: n/a I understand that you are working on the aerodynamics of a moving car. Please correct me if I'm wrong. May I ask why you need to do transient analysis for this?

 October 10, 2008, 09:50 Re: Hi paul , Prasad ... from Adrian #4 Adrian Guest   Posts: n/a Hi matey Thank for your concern on my works and I working with cars and The flow pattern aroumd the car is highly unsteady beside the flow behind the car is separated so to get a good drag and lift result I guess that I must do unsteady analisis and to star this analysis I need some values of Time step size(s) Number of time steps and Max. Iterations per time step Greetings Mateys and take care

 October 10, 2008, 14:01 Re: Hi paul , Prasad ... from Adrian #5 Will Guest   Posts: n/a To start off I would suggest using the time it takes the freestream flow to pass through one cell.

 October 10, 2008, 16:05 Re: Hi paul , Prasad ... from Adrian #6 Prasad Guest   Posts: n/a For a car speed of 100 m/s (or avg speed of incoming air - something like avg wind tunnel air speed), I would start with a quarter of a milisecond. But again, it depends upon the solution stability.

 October 14, 2008, 22:24 Thank you all paul , Prasad ... from Adrian #7 Adrian Guest   Posts: n/a Thank you guys I will try anything else to do this test? I mean another advice?Can you tell your experience in cars if you did some thank you Adrian