SimScale CAE Forum

Outlet velocity doesn't make sense (says air is traveling at 5000 m/s !)

Hi. I’m new to this platform. I wanted to simulate the air flow inside a Venturi tunnel. However, I definitely think I’ve set up the simulation wrongly as according to the post-processing results the air out of the outlet would be traveling at more than 5000 m/s , which is certainly not the case! Maybe I’m visualizing the statics wrongly. Could someone give me an hint on what I’m doing wrong? A massive thank you to everyone replying.

project link: https://www.simscale.com/workbench/?pid=1790336069554270126&rru=07b89115-0cc0-4a3d-937e-d797f1e03a87&ci=ad9793f0-eded-4c4f-a6bc-c4a9bfc3eb59&ct=SOLUTION_FIELD&mt=SIMULATION_RESULT

Hello,

This simulation is a steady-state incompressible operation. This means that if a particle goes into the domain, another particle has to exit to satisfy mass continuity.

In short, we have a huge area at the inlet and a relatively small velocity. The volumetric flow rate is V_inlet*A_inlet:

But the area of the outlet is far smaller. As a result, the velocity goes up to make up for it. In the end:

V_{inlet}*A_{inlet} = V_{outlet}*A_{outlet}

Cheers