[overture] Re: mast-sail

  • From: Bill Henshaw <henshaw@xxxxxxxx>
  • To: overture@xxxxxxxxxxxxx
  • Date: Thu, 03 May 2012 16:08:02 -0700

Hi Alessandro,

     A moving "body" can consist of multiple grids that overlap on the body.
The Integrate class (see the otherStuff.pdf documentation and the test routine
in Overture/tests/testIntegrate.C) knows how to
compute surface integrals even when grids overlap on the surface.
When you define the moving grids you will see printed the list of grid faces
that belong to that body (at which point you can optionally remove some
faces if desired). These are the faces that will contribute to the force
calculations.

 I hope that answers your question.

...Bill


On 05/03/2012 02:02 AM, Alessandro Orchini wrote:
Hi Bill,

it's  clear to me that I can define multiple grids to move, my doubt is how 
overture evaluate the forces on shared grids.

Let us say the physical boundaries are given by

1)rod-grid
 __
|    |
|    |
|    |
|    |
*   *
*   *
*   *

and

2) stretched-cylinder-grid

          *   *
          *   *
          *   *
     -----     ------
    |                |
    |                |
    | ________ |

(my best cylinder in ASCII...)

where I've indicated with * the shared boundaries and with lines - | _  the 
unshared ones.

The the whole grid I move by saying
"moving grids... specify grids... stretched-cylinder-grid and rod-grid"
 is given by

1+2)
           __
          |    |
          |    |
          |    |
          |    |
          *   *
          *   *
          *   *
     -----     ------
    |                |
    |                |
    | ________ |

and this is ok, the shared boundaries have been superimposed.

In the MovingGridsClass I read that the program iterates on each point of each 
sub-grid to evaluate the fluid forces/torque on the body

{
...
(for b=0, b<body, b++)
integrate(I1,I2,I3,f)
...
}

Are not then the shared points * counted twice in this way, one for each 
sub-grid? Or, if there's a routine in the shared configuration that avoid this, 
where is located in the code?

Thanks!

Alessandro





On 04/25/2012 12:34 AM,
Hi Alessandro,

On 04/25/2012 03:50 AM, Alessandro Orchini wrote:

    Hi all,

    I want to generate a grid similar to the 2d mast-sail grid in the examples, 
and then make this grid move under the RigidBodyMotion class.

    I noticed that actually in this way I build up 2 separate physical boundaries 
("sail-grid" and "stretched-mast-grid" in the sampleGrids), that are connected 
sharing a part of the boundary.

    I wonder if is then possible to run this grid under the RigidBodyMotion 
Class:

    Which grid(s) should I move?
    If both of them, does the shared boundary option take into account that 
part of the sail is included in two different grids when computing 
fluid-dynamic forces on the whole body?


This should work. After defining the type of motion you can choose multiple 
grids to move. The forces
will be computed on the entire body.


...Bill

Other related posts: