Learning Forum

[NimaNZ]

Hi Everyone,

The geometry in my simulation is a cubic bluff body inside a domain. Domain has an inlet, outlet, and symmetry boundaries. The location of the coordinate is placed at the center and front of the cubic body. Is it necessary to specify the reference pressure location on the inlet bounady in operating boundary conditions? if I leave it at the surface of the bluff body, there would be a problem?

[Karthik Remella]

Hello Reference Pressure is important for incompressible flow simulations without any pressure boundaries. This helps fix the pressure in the computational domain to a known value. If I understand your simulation, the location of the reference pressure should not affect your results. If you wish to read more about the reference pressure location, please have a look at the following link from the Fluent User's guide.
8.15. Using a Reference Pressure to Adjust the Gauge Pressure Field (ansys.com)
Karthik

[NimaNZ]

Thanks very much for your reply. Exactly, it should not have any effect as it had not till I changed the location of the coordinate from the edge of the bluff body to the front face of it and also changed the gravity direction from y to z, then it gives me the negative pressure on the windward side of the bluff body on which we should have stagnation point (as max pressure). Do you think there would be any problem when we draw the sketch based on z-direction? it seems fluent always takes y-direction as the gravity direction

[Karthik Remella]

Hello Could you share a screenshot of your computational domain? And the operating conditions settings? And the static pressure contour? Please embed them into this post.
Karthik

[NimaNZ]

Sure, here is the domain

and here is operating conditions:
I don't have contours as it's running on HPC, but the probs in locations at which we should have the highest pressure show negative values. I ran the same mesh on RANS and it's solving correctly, but on LES gives weird results?
Could it be because of partitioning? I just set it to 80 core we setting up the model, while in my mesh the domain has divided into 26 partitions.

[Karthik Remella]

Hello You could try to save (or write) an image of the contour to show your results.
I still stand by what I said earlier - Reference pressure location should not affect the results for open boundary incompressible flows.
How is the convergence on your LES run?
Karthik

[NimaNZ]

thanks for your reply
I actually changed the coordinates location from bottom center of bluff body to the bottom corner and it doesnÔÇÖt give negative pressure anymore;
the convergence for each iteration will pass the criteria of 1e-6 for continuity and 1e-8 for momentum.
Is there any possibility that my software has bugs?