Greetings forum users,
I'm trying to model Poiseuille flow in DualSPHysics. However, I run into quite a lot of problems. (I will present quickly what I did and then was goes wrong).
For modelling Poiseuille flow, I create a 2D case using the DesignSPHysics plugin for FreeCAD. I create 3 objects, top & bottom which is solid and the center is fluid. I then introduce a constant force (Using example 04_ExternalForces) and enable x_periodicity. I know that a proper "inlet" and "outlet" are not yet added to DualSPHysics 4.2 but will be added in next version so I was trying to use this work-around.
Now the actual problems.
Firstly, my velocity (V_x(z)) never reaches a constant value, it keeps fluctuating quite a lot over time. I let the simulation run for a relatively long time (100 seconds) and I applied a constant force of 0.5 m/s^2 over the whole simulation.
Secondly, I know there are some boundary issues with SPH, but I get too much of a deviation. The velocity very near the walls is quite high and not close to 0 (I believe the no-slip boundary condition is set automatically, please correct me if I am wrong).
Thirdly, the velocity profile across the 2D pipe is not symmetrical, I noticed that the hyperbole is shifted slightly towards one side (usually lower velocity at bottom of the pipe). I do not know what causes it.
My ultimate goal is to simulate blood flow (multi-phase, Re~100), so I was trying to benchmark simple Poiseuille flow.
If anyone got some tips/directions or explanations I will gladly hear them. Additionally, I tried adding figure files but it was not allowed, if there is a need I will try to post some results (and possible input).
Much appreciated already,