Hello,
I want to simulate forces which act on a particle in the water. In the following pdf link you can find a tutorial which is similar to my needs. But still i cant figure it out how to calculate acting forces on a planar body which is composed of two different materials.
First i guess i need to choose appropriate pyhsics module. ( fsi or laminar flow or something different?)
Then i need to choose right boundary conditions but my body is in still water there is not going to be any flow of water.
Then i need right meshing which i dont know anything about.
Please help me i will really appreciate your help.
In the attached file you can see the forces acting on a particle in the water.
F_b = Buoyant Force
F_g = Gravity Force
F_d F_s and F_m are ignored.
hello.
1- choose laminar flow since you deal with steady state,
2- water adheres perfectly to the sphere so the non slip condition is observed and the relative flow velocity is zero. in the watet
- pick your flow type depending on the Reynolds number. In many cases, the SST model is a good choice if you are in a transition regime from laminar to turbulent or even are in a turbulent regime.
- The buoyant force just depends on your particle volume and the density of the fluid. As water is not compressible, the buoyant force is a constant volume force.
- gravity is also constant
- the drag force is the one you are calculating from the fluid field
For your geometry, it might be necessary to have a very fine boundary layer around your particle so be able to resolve a proper boundary layer.
In this paper:
http://www.dtic.mil/dtic/tr/fulltext/u2/a263650.pdf
a correlation for the drag coefficient of deformed droplets (deformation between sphere and disc) is given (equation 10). Maybe that helps!
First of all thanks for your replies,
OK i understand the physics part but i can not implement it on to the comsol.
There are lots of dependencies, boundary conditions, initial values and from what i read there are always different solutions in the web.
ı tried to make using FSI module but i wasnt successul and tried laminar flow and solid mechanics i also couldnt succed in.
So what i need is step by step instructions for simulating forces.
i found rising bubble example in the web but it use two phase laminar flow and i need one phase and one solid particle. please help me
http://www.comsol.com/model/download/142689/models.cfd.rising_bubble_2daxi.pdf
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