## Fluids

#### Velocity inlet Boundary Condition

• rumth
Subscriber

I have inclined two (02) inlets. Each of them make angle at 15 degree with the axis (centerline). My velocity magnitude is 558.05 m/s . To get the expected velocity from the inlet, I need to apply velocity components option of the boundary condition. How can I use it?

Ansys Employee

Hello,

For velocity inlet, you can define it by three methods. The defualt method of normal to boundary works in many cases.

If you have velocity components in x,y and z then you can use components option.

Regards,

Keyur

• DrAmine
Ansys Employee

Just to add here: Setting the velocity inlet in a compressible flow is "lazy" as you may know this value but it's not the full boundary condition. Stagnation information for compressible flow are quite important.

• rumth
Subscriber

Hi Keyur,

Thank you for your reply. While I am using normal to the boundary, the flow comes like straight line although my inlet is inclined.

Regards,

Raju.

• rumth
Subscriber

Hi Amine,

I am using incompressible flow.

Regards,

Raju.

Ansys Employee

If its straight line normal to boundary then using normal to boundary is ok. If straight line means parallel to axis then you may need to use components.

Regards,

Keyur

• Rob
Ansys Employee

Looking at the image the inlet tube is at 15 degrees, but you've got the inlet plane perpendicular to the axis.

• rumth
Subscriber

Hi Rwoolhou,

Thank you for your reply. The inlet tube is inclined at 15 degree from the axis. How can I get expected flow pattern?

• rumth
Subscriber

Hi Keyur,

Your comment is not clear to me.

Raju.

Ansys Employee

Hi,

With latest image, looks like your inlet is at 15 degrees. Its ok.

Now when you use normal to boundary option, it automatically will be at 15 degrees from axis. So I think you can go ahead and use normal to boundary option.

Regards,

Keyur

• rumth
Subscriber

Hi,

I am doing so but not getting the expected result !

Raju

Ansys Employee

Can you please explain more on expected results. What exactly you are looking at after running the case?

Regards,

Keyur

• rumth
Subscriber

After setting normal to the boundary, getting the flow like this image whereas my expected flow pattern from the inlet is like previous image.

Ansys Employee

I dont see any problem in this.

Explain your settings. Insert images of the geometry, mesh.

Regards,

Keyur

• Rob
Ansys Employee

OK, I think it's a definition problem. In your sketch the nozzle is at 15degrees to the axis. In your (CFD) geometry the port are perpendicular to the axis. So, you've set the inlet correctly for the sketch but not the CFD geometry.

Either alter the CAD to mimic the sketch or use the components option in the velocity bc to set the direction as required.