Scale down the model
 

Hello Dear Friends can anyone tell me how to specify the inlet and outlet boundary conditions when i have scalwd down the model to some smaller dimensions. Please guide me on this

1) Why did you scale it down?
2) What kind of inlet and outlet b.c. do you have?

Dear Sir, the thing is that i have a long 1.5 m * 20 m pipe through which compressible flow enters and exits in the vaccum vessel maintained at 0.01 milibar. i was thinking if i could scale the model to 25 % then i will get the results fast. i have pressure inlet condition as 0.4 bar and pressure exit as 0.01milibar. so can i scale down the model i such a way that i could scale down my boundary conditions also and do you think the pressure drop of scale down model will be of use for the original model?

Thanks in advance.

I don't understand the benefit of scaling a simulation down. If you don't keep the Reynoldsnumber constant during scaling, your results will be useless. And if you do so, you don't save any computational time.

hi shahid
 

i think the scaling rule for your problem will be Mach no. similarity (not 100% sure) and applying it you will reduce your dimensions (saving lot of time) and other variables (pressure, velocity etc.) will be adjusted by the similarity equation. Please refer standard books, papers for accurate details. Good luck.