[Sati Ullah]

Hey Everyone, I hope you all are doing well.

Problem Statement: I simulate a stationary and fixed Pelton bucket. The bucket is hit by a slurry flow. The purpose of the simulation is to investigate the erosion in the Pelton bucket due to the presence of sand particles in the incoming water. The problem that I am going to ask for your assistance with is my solutions never converge after a couple of attempts. I have played with several parameters, which are all elaborated well below.
I would request you to please share your kind suggestions for catching up on convergence after looking into the entire scenario.
Geometry Description:

I am simulating a Stationary Pelton Bucket, mounted to fixed support to compute sediment erosion by passing slurry flow. Water strikes the fixed bucket at 90 degrees. The bucket is enclosed in a casing (a rectangle is first sketched in Design Modeler and then extruded). A nozzle is installed at the inlet (top of the casing) to enhance the velocity. The water gets escapes after striking the bucket via the outlet (entire bottom face).
A picture of geometry is attached below for a good understanding of the scenario and well-articulated coordination.

https://drive.google.com/file/d/1tDu...ew?usp=sharing

Meshing Details:
I used hexa dominant mesh type for the casing and nozzle body and Tetrahedral for The Pelton bucket.
I tried different no. of cells to catch up with solution convergence. Maximum I have tried up to 16 lakhs cells and min of one lakh in different simulation setups.
I tried both physical preferences, CFD and Mechanical.

Setup:
I switched on the energy equation and turbulence model. I tried both K-Epsilon (2-equations, Standard, and realizable) and RSM models.
Also, I switched on the DPM model to find erosion. I chose the surface injection type in DPM. I entered the same velocity in injection for sand particles as that of Fluid velocity.

I run both steady and transient simulations for the said scenario. I have tried different values for residual monitoring, varying from 10^-3 to 10^-10. But the solutions do not head towards convergence in any case.

Boundary Conditions:
1) velocity inlet: I chose a velocity inlet on the top face of the nozzle mounted on the top face. the velocity magnitude is 30 mps.
2) Outlet: I choose the outlet (the entire bottom face) as a pressure outlet with gauge pressure as zero.
3) The Pelton bucket is considered a No-slip, stationary wall.

Dear Researchers and Scientists, I shall be highly obliged for your kind assistance/suggestions pl.