Learning Forum

[Xbuddyin]

Dear Friends,

I am trying to understand the "Pressure Inlet" condition on my convergence solution: I have Buyoncy Driven Flow problem:

I have fluid which is at the Static Pressure (static):101325Pa, which I input into (BC) using the Supersonic/Initial Gauge Pressure (Pa): 101325. and outlet pressure is 95000 Pa

I am not sure what to put in the Gauge Total Pressure: manual suggested it should be stagnant pressure= static pressure + dynamic pressure. but for the dynamic pressure, I should have the mean velocity of the fluid. In my application, I do not have any information about the mean velocity. Imp: Do I need to assume mean velocity in the dynamic pressure?, for example, if we have water, Density: 1000kg/m3 and Velocity: 5m/s (assume) gives me Dynamic Pressure of 12500 Pa then I get the Stagnant Press=101325+12500=113825Pa? I get the following graph for the residual? Is this correct?

A. Pressure Inlet Boundary Condition with 113825Pa.

[Karthik Remella]

Hello The total pressure is how you have defined. The Supersonic/Initial Gauge Pressure must be specified if the inlet flow is supersonic or if you plan to initialize the solution based on the pressure inlet boundary conditions. I would specify the total gauge pressure as a known quantity. One point to note - please make sure that you are capturing the gravitational head of the fluid correctly when you are specifying these inlet and outlet pressures.
7.4.3. Pressure Inlet Boundary Conditions (ansys.com)
Yes, the convergence for these two cases should be different and hence the different residuals. I would read more into the solution than the residuals, TBH.
Karthik