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 Dimitris Tavernarakis November 3, 2000 09:56

ansys & 3d cfd

How is it possible for someone to make a 3D CFD analysis with ansys 5.5.3. My problem is a airplane wing.

 Evan November 3, 2000 13:36

Re: ansys & 3d cfd

You would need to have FLOTRAN to correctly solve your problem. ANSYS itself is very weak in solving fluid flows, basically limited to flows with heat-flow analogies.

 Dimitris Tavernarakis November 4, 2000 20:27

Re: ansys & 3d cfd

I'm using ansys multiphysics which has flotran and I've already have made several analysis in 2D ( more like Quasi 2D) but my problem is, if I have a 3D drawing where do I apply the boundary conditions.

 Pantelis Kiotsekoglou December 11, 2000 09:24

ansys & 3d cfd

Well, first I´m happy to find a greek Fluid Dynamicist who is involved in the same problem field as me.

The next are the boundary conditions. Very significant for applying boundary condition is the geometry of the model itself. On Boundary Areas or lines where no fluid is exchanged with the enviroment, all e.g. velocities can be set to zero. Better you type zero in! Before you start generating a model you should already have some boundary conditions, do you?

 Dimitris Tavernarakis December 11, 2000 17:57

Re: ansys & 3d cfd

For the begining, My boundary conditions are the speed, and the air characteristics. But I don't understand, If I have a 3D wing and nothing else (not even a plane in space)what should I do to make an analysis

 Pantelis Kiotsekoglou December 12, 2000 07:55

ansys & 3d cfd

The first most important step before starting an Analysis in CFD is the Definition of a Control Volume. This means you have to create a virtual boundary around your object. The properties of this Control Volume has to be of simple mathematical nature. So that your given boundary conditions are easy to apply.

On the boundary of the control Volume is not allowed to have any gradients of fluid properties or other properties in high- order functions.

Lets take your wing now,first put a big cube around the wing, next, the velocity which the wing is flying with is the boundary condition which you apply on the control volume, in x,y,z directions(first condition). The next one is the velocity of the fluid on the surface of wing geomtry, this is zero! Now you go on and apply a zero speed in each direction on the surface nodes of the wing.

Thats it. Just let the fluid properties be constant over time and temperature, so that the beginning of analysing is very easy. If this calculation has been successfull, go on and change some fluid properties, not to much. Starting a new analysis and so on and so on.