# Egyption Pyramid with All HEXA

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 March 22, 2001, 17:16 Egyption Pyramid with All HEXA #1 Selina Tracy Guest   Posts: n/a Sponsored Links Is there anyone who can make Egyption pyramid with all hexa meshes. I've been trying for a couple of weeks but only to fail. Thanks. Selina

 March 22, 2001, 18:12 Re: Egyption Pyramid with All HEXA #2 John C. Chien Guest   Posts: n/a (1). I thought that the big stone blocks used in Egyptian pyramid were six-sided. (2). I think everybody knows that they were far more advanced several thousand years ago.

 March 22, 2001, 20:21 Re: Egyption Pyramid with All HEXA #3 Selina Tracy Guest   Posts: n/a Do you really think all of the bricks are six sided. What about the very point of apex. Thanks. Selina

 March 23, 2001, 00:15 Re: Egyption Pyramid with All HEXA #4 John C. Chien Guest   Posts: n/a (1). A point can be a small square. Even a needle point is actually rounded.(2). There is no way one can compute flow around a point. This is exactly the reason why the computational geometry is not the CAD geometry. (3). In CFD, the geometry and the mesh are handled together, and both must be modelled.

 March 23, 2001, 02:55 Re: Egyption Pyramid with All HEXA #5 Selina Tracy Guest   Posts: n/a Topology for Selina and CFD for John. Marc

 March 23, 2001, 03:56 Re: Egyption Pyramid with All HEXA #6 John C. Chien Guest   Posts: n/a (1). A finite length cylinder with constant diameter is a round cylinder. (2). A finite length cylinder with zero diameter at the top is a cylindrical cone. (3). A finite length square with constant cross-sectional shape is a square cylinder. (4). A finite length square with a zero cross-sectional area at the top is a pyramid. (5). They all have the same topology. The cross-sectional shape is self-similar.

 March 23, 2001, 04:03 ICEM etc: Egyption Pyramid with All HEXA #7 Krylov K Gorky Guest   Posts: n/a i've just send an email to icem etc. to see if they can do it. but i doubt it. it's not a sort of question that a company can give an answer. it's too academic if you stick to math. let's see. googluck to all. -Kryl

 March 23, 2001, 05:19 Re: ICEM etc: Egyption Pyramid with All HEXA #8 Frank Guest   Posts: n/a Very funny to read your discussion. What about simply deviding a hexa into 6 pyramids. It's base consists of the hexa faces and the endpoint of the centroid. The faces are described via bi-linear shape functions (forget about splitting a face, that has 4 vertices in to 2 triangles -> that is the stupid way to do it). With those pyramids you can build up every topology you like. Not only hexa, but also degenerate a quafrilateral face into a triangle. Taking a structured flow solver and degenarating a hexa into a pyramid is probably not a good thing to do, since structured solvers are very picky, due to utilized metrix terms (not computing in physical space looses rubustness) Frank

 March 23, 2001, 07:03 Re: Egyption Pyramid with All HEXA #9 Joern Beilke Guest   Posts: n/a Just divide the pyramide into 2 tets. Now each tet can be divided into 4 hex-blocks. I just created a mesh using this topology. If anybody is interested I can put the stuff somwhere.

 March 23, 2001, 07:40 Re: Egyption Pyramid with All HEXA #10 Joern Beilke Guest   Posts: n/a Here are the files: http://www.beilke-cfd.de/pyramid/pyra1.gif http://www.beilke-cfd.de/pyramid/pyra2.gif http://www.beilke-cfd.de/pyramid/pyra3.gif and the mesh in Grid3d and Nastran format: http://www.beilke-cfd.de/pyramid/pyra.g3d.gz http://www.beilke-cfd.de/pyramid/pyra.nas.gz Have fun

 March 23, 2001, 09:50 Re: Egyption Pyramid with All HEXA #11 John Chawner Guest   Posts: n/a There are at least three topologies that come to mind immediately. 1. Split the bottom edge of each triangular face. Then each triangle is now four sided and you insert a quad mesh. 2. Insert a node into the middle of each tri face and then bisect each edge of the tri face. Now the tri faces are subdivided into three quad regions. 3. Use a singularity at the vertex. -- John Chawner - http://www.Pointwise.com - Gridgen: Reliable CFD Meshing

 March 23, 2001, 12:01 Re: Egyption Pyramid with All HEXA #12 John C. Chien Guest   Posts: n/a (1). Very nice. (2). It is a multi-block, structured hex-mesh.

 March 23, 2001, 13:37 Joern: Egyption Pyramid with All HEXA #13 Selina Tracy Guest   Posts: n/a Wonderful! But I have to say I did not defined my problem well. What I meant was generating pyramid with all hexa while keeping only ONE FACE BASE. Sounds TOUGH! Could you try one more time if you can do it easily? Selina

 March 23, 2001, 13:40 Re: Egyption Pyramid with All HEXA #14 Selina Tracy Guest   Posts: n/a Joern did a wonderful job. But I had to redefine my problem. Let's Make the pyramid with all hexa while keeping ONE FACE BASE. Thanks. Selina

 March 23, 2001, 14:21 Re: Joern: Egyption Pyramid with All HEXA #15 John C. Chien Guest   Posts: n/a (1). I had already given you the answer, that is, you create a square cylinder,create a single block hex mesh in it and then transform the mesh such that the tip area goes to zero. Then you will have one single block hex mesh. (2). That is the standard answer.

 March 26, 2001, 03:32 Re: Egyption Pyramid with All HEXA #16 Robert Schneiders Guest   Posts: n/a Hi, check http://www-users.informatik.rwth-aac...erts/open.html Regards, Robert Robert Schneiders MAGMA Giessereitechnologie GmbH D-52072 Aachen Kackertstr. 11 Germany Tel.: +49-241-88901-13 email: R.Schneiders@magmasoft.de www: http://www-users.informatik.rwth-aachen.de/~roberts/

 March 30, 2001, 04:15 Re: Selina: Egyption Pyramid with All HEXA #18 Selina Tracy Guest   Posts: n/a Your answer is one of the best that I have got for this geometry. Yes, I have already read the papers you recommended. But still the clouds are hanging over my head. I am working on an alogrithm which should come from "the simplest recursive formula" so that it can be used practical purpose. Inner topology that has all the features of geometry. Sounds too optimistic. Selina

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