[amrit]

hello,
m learning FLUENT now so as to do a project... i have been trying to simulate a swirl flow in a cylindrical pipe ... but the solution is not converging and am facing problems while trying out various things... so could ne1 plz help me out

thnxx in advance!!

[amrit]

plzz guys .. i really need sm help..

[delfel]

Hi Amrit,

More details are probably needed to determine why your solution isn't converging. Can you tell us any more about the problem and your model? Also, what is the convergence history like -- do the residuals diverge immediately or after many iterations?

The most common problem for people new to CFD are poor mesh elements or improper boundary conditions. My first tip would be to display contours of your mass residuals and see what the grid looks like in the area with the highest residuals. You should also examine the mesh in Gambit to see what your aspect ratios, skewness, etc. are like and correct any poorly shaped volumes.

If your mesh is good enough, other tips to achieve convergence are to start with better initial conditions (I'm assuming you used the default values). You can also start with the first order solver, then switch to the second order solver once you've achieved a converged 1st order solution. Finally, you could get a converged solution at a low flow velocity/pressure/etc., then slowly increase the velocity to the desired levels.

Hope that helps,
-sean

[santu]

I am trying similar type problem. my problem is a 3D vertical cylinder tube which have three inlet and one outlet. In the main pipe water is flowing and in the branch pipe air is injecting.I need to study the swirl flow of the air inside the water. My boundary condition are at inlet all three pipes mass inlet and pressure outlet in the outlet. I am using K-omega sst turbulent model for simulating my problem.

Is my boundary condition and model good .

I am unable to get converge my problem. I am doing unsteady simulation. I decrease the URF values.

I have doing hex mesh with quality 0.45 , aspect ratio 21. i think it is good for meshing geometry


Can anybody help me.