CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   CFX (http://www.cfd-online.com/Forums/cfx/)
-   -   difference in results between 2D and 3D (http://www.cfd-online.com/Forums/cfx/24879-difference-results-between-2d-3d.html)

 Michelle December 4, 2007 03:43

difference in results between 2D and 3D

Hi everyone, I'm simulating a flow in a pipe with dispersed droplets in continuous vapor. My objective is to obtain results for compressible, inhomogeneous model but my initial results are not those expected by my professor, he asked me to simulate first a basic model. So here's my basic setup: - constant properties, no heat transfer - laminar model - free slip at wall - schiller for drag - for the inlet, the vapor is 2x faster than droplets I simulated for both 2D and 3D. As far as I know, the velocity along the pipe should not vary radially (since laminar and free slip).I got that result using 2D but for 3D case the velocity varies especially at the wall. Do you have any theoretical explanation about this one? Please help me. Thanks a lot guys!

Michelle

 wan December 6, 2007 00:56

Re: difference in results between 2D and 3D

hi, you can try read this 2 journal..might give you somthing. 1.laminar fluid behavior in microchannel using micropoar fluid theory. by Ian Papautsky

2.The study of flow characteristic of curved microchannel.by wei-hua yang.

have a nice day.

 CycLone December 6, 2007 11:59

Re: difference in results between 2D and 3D

Also make sure your 2D and 3D meshes are consistent (i.e. revolve the 2D mesh to get the 3D mesh), otherwise you may be looking at mesh dependancies.

-CycLone

 Michelle December 10, 2007 02:59

Re: difference in results between 2D and 3D

Thanks Wan and Cyclone! I guess the solution didn't converge properly and it wouldn't because the actual flow is not laminar. I lowered the velocities and I got the expected results for laminar. Thanks a lot for the responses!

Michelle

 All times are GMT -4. The time now is 17:22.