Learning Forum

[echoecho]

Hello I'm trying to simulate the flow-generated sound due to obstruction in a pipe using Ansys Fluent R19.2.
It's a 2D setup. My domain is set as a small pipe connected to a half-circle large environmental domain.
I use velocity inlet and pressure outlet at the environmental boundary.
I use the pressure-based solver (coupled scheme) and ideal-gas law for air.
The simulation is first run as steady flow, after which it is changed to transient.
The problem is that there is "reflected" wave from the outlet boundary at the start of the transient simulation, it propagates into the domain (black arrow in the following figure). It appears to be artificial.
Any suggestion to eliminate this phenomenon? Any information is appreciated. Thank you!

[echoecho]

I wanted to add that the Non-Reflecting boundary condition is used at the outlet.