Greetings DualSPHysics users,
I'm trying to simulate 3D irregular tube flow. The results are less than satisfactory. Initially I simulated 2D low Reynolds Poiseuille flow (Re <<1), which had excellent results. In the end I simulated 3D Poiseuille flow (Re=500) which still had excellent agreement with the analytical solution. All of that was done using a straight tube, and the next step was to use a tube which had a bulge (quick expansion and then quickly narrowing again). I have attached 2 images, one shows the full structure and the other one shows the "cut" structure (shortened).
I used my previous .xml file, added in the new structure file and modified the domains a tiny bit. Due to the length of the structure, the previous dp (=0.00005) could not be used (~70 million particles). Dp was changed to 0.0005 to allow an acceptable computation time.
The result was disappointing, too high velocity and a Poiseuille flow at the exit of the pipe was not achieved. I have attached an image showing the profile across the pipe (Vmax is supposed to be 1 m/s, it is ~ 2 m/s)
What I expected to see is a fully developed profile at the exit of the pipe while at the ~centre (At the bulge) it would get more messy (Somewhat turbulent).
Things to note:
- I'm using kinematic viscosity since artificial viscosity provided not good results in the previous steps and kinematic viscosity value will be changed in the future (Extremely desired)
- Dt's were adjusted during the simulation
- 17850 particles out of 850k were removed (99% due to Rhopout)
My question comes down to, what is the best approach to proceed with this problem? My ideas were:
- Increase number of particles even further (At the price of computation time, which is quite limited)
- Try to change some of the parameters in .xml and perhaps use Delta-SPH / Shifting (Unlikely)
- Try using artificial viscosity (Quite undesired)
If anyone has any comments on my methodology or on how to proceed further, it would be greatly appreciated. If any extra information is required, I can provide it. Additionally, I have uploaded a .txt version of the .xml file.
Edit: I somehow cannot make the pictures appear in the text, if I add them the text disappears. Hopefully they are still accessible.