Learning Forum

[ahmed.hassan902]

Hello everyone!

I am still beginner using ansys fluent.

I was simulating the flow over a semi-circle obstacle and I was expecting to find symmetrical velocity contour over the obstacle ,as I was not expecting to find recirulation zone downstream.

I don't know what's wrong with my setup.

[SRP]

 

Hi,

you might be encountering flow separation and the formation of a recirculation zone behind the semi-circle, which is quite common for flow over bluff bodies

 

[ahmed.hassan902]

Yeah I know that the formation of a recirculation zone behind a bluff body is common ,but I don't think it is common for inviscid flow.

[Petros Diakoumakos]

Hi,

Reynolds number must be less than 5 in order for the flow to remain attached. For this case based on the contour and assuming air as the medium, the cylinder diameter should be ~5μm to have a Re<5, which I guess it is not. Thus you are in the turbulent regime and flow recirculation is expected.

[ahmed.hassan902]

Since I have chosen the inviscid model, which means viscosity is zero, the Reynolds number (Re) is approximately infinity. Therefore, by changing the diameter, I don't think it will change anything. Does this mean that I will always expect separation in inviscid flow?