[hellsblade.91]

I am trying to simulate flow (attached result file). I am running the sim for various depths (1-6mm) and various pressure (6-24 bar) . attached file is .. bar and .. depth

Can someone tell me how will my results get affected if i run the sim in explicit or via impilict i am getting lower values of mass flow rate at outlet in explicit

also how does the time step size and no of time step affect my sim (higher or lower value )

Currently i am running my simulation for 80 time steps with a time step size of 1 s (implicit)

[DEd]

In order to get help you need to describe your problem/setup much better.

- what do you mean by depth?
- what's your boundary conditions?
- what fluid? Incompressible liquid or compressible gas?

[hellsblade.91]

Attached you find a measurement of what i mean by depth ( 1mm in this case). I am running other sims between 2-6 mm

Its a compressible flow- air in my case

BC

Pressure inlet
Pressure outlet

[DEd]

Ok, so is this a 2D case or are the sides walls?

So you have some kind of cylindrical nozzle. With >6 bar the flow is critical and the outlet is full of shock waves (se picture for example). Are you trying to resolve these pressure field? What's the purpose of the calculation? Is it to calculate the mass flow through the nozzles or something else?

[hellsblade.91]

The purpose of the calculation is to check the max velocity from the outlet when the depth and pressure is varied and zes the mass flow outlet is also calculated at the outlet

As this involves high pressure 6 to 24 bar density based solver needs to be used as its a highly compressible flow ?

Also I am getting reversed flow at some of my faces of outlet how do i check which faces or cells is there an option in fluent ?

[DEd]

"As this involves high pressure 6 to 24 bar density based solver needs to be used as its a highly compressible flow ?"


Yes, for sure. And also probably more refined near the nozzle exit. Also, your geometry seems to simple (is this a real geometry?). It's probably crucial for the mass flow how the fluid twists and turns in the nozzle. Have you tried doing a calculation with a single nozzle first? As the flow is critical the mass flow shouldn't be affected by the outlet conditions (the other nozzles).


"Also I am getting reversed flow at some of my faces of outlet how do i check which faces or cells is there an option in fluent ?"

Just do a contour plot on the outlet face showing the normal velocity.

[hellsblade.91]

Thanks Daniel Refer the attached picture