Turbulent Pipe Flow Validation Error

Using SimScale Fluid Flow / CFD
1

I was able to repeat the results in this validation:

However, if I increase the velocity to 4.664 m/s, the pressure loss that is calculated is almost twice as high as that calculated from the Darcy-Weisbach equations. Is this because the higher the velocity in the pipe, the longer the pipe needs to be to get to a fully developed flow (i.e. Entrance Length) or is it something else that is deviating? The entrance length does not change much (+30%) with going to a higher velocity so I didn’t think that would have that much of an impact.

2

Hi @mas985,

I will tag my colleagues @sjoshi and @gholami here. They might give you some good input for your problem.

Cheers,

Jousef

3

Turns out that the mesh resolution was too course. I used the next level mesh (moderate) and now the results are within 10% of DW.

Are there any good rules of thumb regarding mesh resolution or is it always trial and error?