Learning Forum

[syed123]

Hello,

I keep getting this error shown below in the image. I changed fff_Nacelle to solid from air as this is a solid object. How do i fix this error.

Regards

[Karthik Remella]

Hello,nPlease double-check your named selections. It would seem like one of your flow boundary (inlet or outlet) are specified on the solid object. Carefully investigate the cell zones and their neighbors on all your boundaries. You will find the issue.nKarthikn

[syed123]

hello,nnThank you for your help. I have solved the error by making the outlet fan a wall boundary condition. nI have another question relating to boundary condition. nI know my air flows at velocity 236.768 m/s and put a velocity inlet boundary condition there. However, i am not sure if i am supposed to enter an number in the outflow gauge pressure and supersonic/initial gauge pressure. I do have the inlet static pressure of the flow but i am not sure if i should define it here. (I am modelling a turbofan engine but the main area of focus is at the inlet).nI have also defined the outlet to be pressure outlet = 0, i am assuming this tells fluent that the flow exits here.Regards

[Rob]

If the material density is pressure dependent then the outlet pressure matters, otherwise it's just a value to set the outlet at. n

[syed123]

Hi Rob,nnThe material density is not pressure dependent so i have left the outlet pressure = 0. nWhen Run the simulation i get this result:nnThis does not look right compared to other simulation that were run (The contour plane is at the cross-section of the Nacelle). Surely the pressure should increase towards the fan area and the walls of the Turbofan. Do you think this may be a boundary condition problem or a mesh problem or somthing else that i am not aware of.Regardsn

[Karthik Remella]

Hello,nYour material is air, right? At an inlet velocity of 236 m/s (assuming the speed of sound is 340 m/s), you are already at a Mach number of 0.7. The flow is likely compressible. You should be using the ideal gas law for density.nKarthikn

[syed123]

Hello,nnMy turbofan is solid but the control volume is air. I have used ideal gas law for density and Sutherland for viscosity. nBelow shows the contours vector plot. For some reason it does not flow around the Turbofan, i don't know why it doesn't do that. nnHere is the image of the cell zone condition:nnnHere is the Boundary Condition:nnnhere is the Inlet BC: nnand here is the outlet pressure:nnHere is the mesh:nnnI know the mesh control volume needs to be increased but for some reason the flow does not recognise that the solid turbofan is there. I really need to just show how the air flows around the nacelle inlet, i have been struggling to do this, any help would be grateful.Regardsnn

[syed123]

Here is the WorkBench File for the project if you wish to see more in detail.Regardsn

[Rob]

Is the nacelle a separate, connected volume? The mesh image you've attached suggests the two domains aren't seeing each other. n

[syed123]

Hi,nnYes the Nacelle is a separate connected volume. Is the Nacelle mesh meant to be connect via Body of influence?