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Old   August 12, 2008, 02:19
Default free surface modelling...
  #1
NITIN DEWANGAN
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i want to solve the problem of multiphase model. which distinguishes the two different fluids when i draw planes or isosurfaces in CFXPost.

is there any option like patching in fluent?

help me to solve this.. thank you
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Old   August 12, 2008, 02:21
Default Re: free surface modelling...
  #2
NITIN DEWANGAN
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this model will be a rotating type domain, there is no inlet and no outlet.top is open.like a glass.

so please tell me how to write boundary conditions please.

thank you
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Old   August 12, 2008, 22:35
Default Re: free surface modelling...
  #3
Glenn Horrocks
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Hi,

You can either have a mesh with regions defined and use the regions or define a CEL function which defines the region. You can use functions like step() and subdomain.

Glenn Horrocks
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Old   August 16, 2008, 23:30
Default Re: free surface modelling...
  #4
nitin dewangan
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what will the exact expression to make a symmetric curved free surface while rotating a cylinder?

thank you Glenn
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Old   August 17, 2008, 09:57
Default Re: free surface modelling...
  #5
Rogerio Fernandes Brito
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ANSYS CFX Tutorials | Tutorial 15: Multiphase Flow in Mixing Vessel |

This example simulates the mixing of two fluids in a mixing vessel. The geometry consists of a mixing tank vessel containing four baffles. A rotating impeller blade is connected to a shaft which runs vertically through the vessel. Air is injected into the vessel through an inlet pipe located below the impeller blade at a speed of 5 m/s.

ANSYS CFX Tutorials | Tutorial 16: Gas-Liquid Flow in an Airlift Reactor |

This tutorial demonstrates the Eulerianâ€"Eulerian multiphase model in ANSYS CFX. The tutorial simulates a bubble column with an internal tube (draft tube) used to direct recirculation of the flow. This configuration is known as an airlift reactor. Bubble columns are tall gas-liquid contacting vessels and are often used in processes where gas absorption is important (e.g., bioreactors to dissolve oxygen in broths) and to limit the exposure of micro-organisms to excessive shear, imparted by mechanically driven mixers. This example models the dispersion of air bubbles in water. The gas is supplied through a sparger at the bottom of the vessel and the rising action of the bubbles provides gentle agitation of the liquid. Simple bubble columns that are without the draft tube tend to develop irregular flow patterns and poor overall mixing. The draft tube in the airlift reactor helps establish a regular flow pattern in the column and achieve better uniformity of temperature, concentration and pH in the liquid phase, but sometimes at the expense of decreased mass transfer from the gas to the liquid. This tutorial also demonstrates the use of thin surfaces. Thin surfaces are internal two dimensional wall boundaries used to model thin three dimensional features (e.g., baffles, guide vanes within ducts, etc.). The airlift reactor that is modeled here is very similar to the laboratory bench scale prototype used by García-Calvo and Letón.

ANSYS CFX Tutorials | Tutorial 19: Cavitation Around a Hydrofoil |

This example demonstrates cavitation in the flow of water around a hydrofoil. A two-dimensional solution is obtained by modeling a thin slice of the hydrofoil and using two symmetry boundary conditions.

Best
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Old   September 9, 2008, 03:59
Default Re: free surface modelling...
  #6
hariharan
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sir As i am going to design agitator,for my part of project work is going to be in CFD. can u suggest me how to design reactor and agitator, how i want mesh both of them. how could i give boundary condition for it.which one should be rotating and stagnant one. how i want mesh them.
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Old   September 21, 2008, 02:16
Default Re: free surface modelling...
  #7
rkpatel
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thanks
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