Learning Forum

[pahuynh]

Hi everyone, 

I am working on a project that is interested in the pressure changes in a fuel injection rail as injectors open and close. I have four injectors in parallel with a wall on the left side of the figure and an inlet boundary condition on the right of the figure. 

 

I am working on a project that has an inlet boundary condition, followed by a injector inlet boundary condition and an outlet boundary condition. The injector inlet boundary condition is a UDF that says that the boundary condition is a door that opens and closes at the frequency the injector operates at. I am trying to get the 2 different cell zones to allow mass to transport between each other between this injector condition but I cannot get it to work. I know its a mesh interface problem. The two meshes are the same size so thats not a problem with a non conformal mesh. I want to "couple" these two cell zones but how do i do that. I am also working with ansys fluent student if that makes a difference. I suspect there might be limited capability in it. 

[Rob]

I'm not sure what you're trying to do, but think you want to switch an interior boundary to and from wall at a preset interval? Ie block the flow for some period. This isn't overly simple with UDFs as you'd need to access the Fluent Scheme interface (I'm not able to cover that as I neither know how nor am allowed to go into that level of detail on the Forum). However, Execute Commands provides a very good way of doing this using TUI commands.  

Note, if inflow is constant and you're blocking the flow I hope the fluid is compressible. The model is also going to be very unstable as flow abruptly switches on and off. 

[pahuynh]

Hi there, 

Yes the flow is compressible. And yes you are correct in what I want to do. Block the flow for some period by changing the boundary from an interior boundary to a wall.