[Qingsong]

Hi, I'm Qingsong,

Recently I began to calculation ship resistance with free surface. In order to get quick response of my settings, I used less than 1 million nodes of mesh and inviscid flow. It may not generate accurate solution, but I think at least a physical solution. However, I got following strange wave pattern and velocity field.

So, if anybody encountered similar problem and know how to solve it, I will really appreciate that.


Solution 1:
Fluent 16.2, pressure based solver
Inviscid (ship model)
Boundary conditions：velocity-inlet (Fr=0.9) + outflow + ship(wall)+ far field(symmetry)
VOF + implicit
Methods: SIMPLE + Least square cell based + PRESTO! + Second Upwind + Compressive
already patch water region
initialize from air-inlet
Total flow time 1.939s
Mesh number: 0.77 million
Wave pattern and velocity field on free surface images are attached.
Problems:
1. Wave pattern is not physical solution, do you know why?
2. Velocity near inlet is not smooth


Solution 2:
Inviscid (ship model)
pressure-inlet (Fr=0.9) + pressure-outlet + ship(wall)+ far field(symmetry)
VOF + implicit + Open channel flow
Methods: SIMPLE + Least square cell based + PRESTO! + Second Upwind + Compressive
already patch water region
initialize from inlet
Flow time 21.288s
Mesh number: 0.27 million
Wave pattern and velocity field on free surface images are attached.
Problems:
1. Wave pattern is not physical solution.
2. Velocity near outlet is not smooth is higher than other place. This shouldn't be like this.


At the same time, if you are also working on such topic, welcome to discuss together.

Thank you in advance.
Qingsong

[Qingsong]

After refinement of mesh on free surface, problem seems been solved.