How to Handle Momentum Source Adjacent to Inlet?
 

Dear all,

I have a fundamental question regarding the handling of the momentum source that is applied to the inlet. See the channel flow in the attached schematic (just one row of the grid, and staggered grid is used). The upper schematic is the problem statement, in which the user specifies a momentum source in the first scalar cell. Since we use staggered grid (U cell marked be green dash line), when solving the momentum (U) equation, then it seems like we have to move the source location specified by the user a-half-cell forward, as shown in the lower schematic. Physically, this solution is targeting a different flow than the one specified by the user. Does anyone have any experience on this problem?

You can check my schematic of this problem in researchgate: https://www.researchgate.net/post/Ho...acent_to_Inlet

Thanks.

- A source term is specified as a volume internal quantity not prescribed as a flux BC.

- The u and v components have two different control volumes, you have to prescribe the source in the cell for each of both.


I cannot say more if you do not describe the expression of the source

The source term is a constant, for example, 10 N/m^3. Normally, user can specify the source term in the scalar cells. My question is how I can specify them in the u or v control volume. If I just directly move a half-cell, I feel like it is not right.

But if it is constante it has no variation in any direction...:confused:

Yes. The schematic is just one row of the grid. What I am worried about is if user specifies the source term in the scalar cell, can I/should I move it to the u/v control volume directly, as such move will place the momentum source a half-cell different as user defines. I hope I make my question clear :).

What should be the problem if the source is a constant???

The location of the momentum source...User specifies the source in the scalar cell, not u/v control volume.