Detrmination ship resistance VOF method

1brah1M1brah1M Member

Dear all,

 

I hope you are doing well,

I am creating a simulation to determine the ship resistance in calm water, using Ansys academy R1 2019,

I created the mesh using Poly-hexacore using the body of influence sizing and face sizing for the ship the maximum skewness is 0.7,  minimum orthogonal quality is 0.13,

RANS Using SST for viscosity, Implicit VOF open channel, y+ is between 1 and 10 the boundary condition is fig 1

  •  Inlet pressure inlet
  • Outlet pressure outlet
  • Symmetry
  • Bottom side top is walls
  • Ship is wall

the scheme is Coupled, gradient  least-square cell base, volume fraction HRIC, second-order upwind for turbulent and momentum
My question is:

  • Why is the velocity contour in Inlet, I have a drop in the velocity on the water surface Fig2
  • the drag is oscillation and the solution doesn't converge even after 40K iterations the oscillation between 19 and 20 N.
  • I used for the reference value the area of the ship in the X direction, density, and viscosity of water is it right? or should I use the are of the whole ship underwater, density, and viscosity of air this point is confused  me

 

Best regards

 

Fig 1

 

fig 2

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