[HectorRedal]

Originally Posted by FMDenaro

Good, that's what I expected.

However, you still can not be sure of further bugs in your code. The lid driven cavity test-case does not help in this assessment (we can discuss a lot about why) and you should still consider the analytical test-case to compute the solutions on several refined grids both while taking dt/h= constant and using via via refined time step fixing one grid with the smallest h you can use.

For sure, that there are more bugs in the code. One cannot be sure that your software is 100% free of bugs. That is true not only for the code developed by me but for any existing developed code (even commercial).

Not only have I tested my code with the lid cavity flow, but with a test case that simulates a flow through a two-dimensional rectangular channel with non-slip condition in the walls. Solution to this problem is well-known. The expected flow pattern is a parabolic profile.

I have also performed a convergence study taking dt/h constant.
I obtained the same order of convergence than for the lid driven cavity flow with less than 0.1% of deviation error from the theory.

[arjun]

Originally Posted by HectorRedal

Hi Arjun,

I really appreciate your help and support on this issue.

I would like to comment that finally I have found an error in the code when retrieving the value of the pressue from the previous step. There was an initialization error in a loop that iterates over the nodes of the TRIA element.
After having fixed the error, I have tested and it (reducing the time step), and it appears that it is working now.

I have tested with delta T = 10e-6 and even with 10e-7, and the solution does not blow up at all. It really provides quite accurate and good results, at first sight.

Thanks a log for your help.

BR

Glad that it worked out.
This is what makes CFD very difficult that when things don;t work we can not say anything with certainty.