Issue with pressure boundary and gravity in DPMFoam
Hello,
I have an issue with running the DPMFoam solver with a vertical outlet boundary. There does not seem to be a suitable boundary condition for the pressure in this case. With gravity on you will get a hydrostatic pressure field in the internal domain, so setting a fixed value of zero becomes wrong. Does anyone know how to fix this in DPMFoam? Other solvers, such as interFoam, seem to fix this by instead solving for p_rgh. I have tried various other approaches, such as setting the outlet pressure to the hydrostatic pressure, but without success. I notice that the tutorial cases for DPMFoam and MPPICFoam either only have horizontal boundaries or have gravity switched off. Thanks, Eric |
2 Attachment(s)
I have attached two plots illustrating the issue. This is flow through a channel with a constant inlet velocity and without any particle injection.
In the first plot, I have used a fixed value for the pressure at the outlet (right boundary). Here you can clearly see the hydrostatic pressure buildup in the domain. The second picture shows the result when I try to set the pressure to the hydrostatic pressure at the outlet. That doesn't seem to work either. - Eric Attachment 42700 Attachment 42701 |
Hello eric and everyone else,
i have the same problem as you. Exchanging air with water in DPMFoam and causes the exact same issue. I tried also many bc at the outlet and got, when the solver ran, a similar phenomena. Did somebody solve the problem, or could tell me how to implement hydrostatic pressure to the DPMFoam solver? |
1 Attachment(s)
So i tried some more bc combinations and extended the 0-folder a bit(pimpleFoam), leading to no change in both alternatives (simple (DPMFoam) and extended (pimpleFoam) 0-folder). I always get a similiar picture as eric (see attachement).
My example is a simple block geometry with 3 particles on the ground. The Inlet is a fixedValue and the Outlet should just let water out as it comes, which it clearly does not, looking at the screenshot. Am i making something wrong with the boundary conditions? My second assumption is that the DPMFoam Solver (pEqn.H especially) is not made for water simulations. Following are my p and U.water codes: p: Code:
/*--------------------------------*- C++ -*----------------------------------*\ Code:
/*--------------------------------*- C++ -*----------------------------------*\ |
Hi,
Using DPMFoam to study the scour around a cylinder, I started with a classic model without particles in icoFoam. Everything is ok concerning the mesh, fluid behavior... Then, in DPMFoam, with 1 particle and the same mesh, boundary conditions..., when I set g = 0, the simulation converges well and the results match those of icoFoam. But when g = -9.81, U_z, U_magnitude,Courant Number increase at the outlet and the simulation stops. Did you solve the problem ? |
same problem
|
Iīve solved my problem by coupling an Euler-Lagrangian Solver. I did this by adding to the standard pimpleFoam-Solver the lagrangian library.
Since itīs some time I did this hereīs a presentation, where i got the idea with a short but thorough tutorial. https://www.foamacademy.com/wp-conte...les_slides.pdf I hope this helps everyone who got stuck at this exact same point |
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