# Grids

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 October 31, 2006, 16:51 Grids #1 Confused Guest   Posts: n/a I have seen the terminology O-grid c-grid etc..Can someone explain what does each of those letters represent.I'm not sure what to exactly look for to know what they mean.

 November 1, 2006, 05:07 Re: Grids #2 michael k Guest   Posts: n/a O-grids and C-grids are special variants of blockstructured grids. For example if you want to mesh a circular duct you'll get a very bad grid when you are using only one block, because the CV's at the walls will be skewed... In this case you can use a O-grid which means that you have one block in the middle an four blocks that surround this block. So that you'll get this block structure: _________ |\ /| | \___/ | | |___| | | / \ | |/_____\| And a C-grid would be something like this (only upper half): __________________ |\ | | \ | | \ | | \_____________| | | | | | | | | Sorry for my poor English Michae

 November 1, 2006, 05:08 Scetch didn't work... *NM* #3 michael k Guest   Posts: n/a

 November 1, 2006, 09:04 Re: Grids #4 myron Guest   Posts: n/a See this for an O-Grid: http://www.ansys.com/products/icemcf...hexa/ogrid.htm A C-Grid would be with one side of the 'O' removed.

 November 2, 2006, 11:00 Re: Grids #5 Mani Guest   Posts: n/a myron, that looks like a bad example. There is a small O-grid embedded in the animation, but if you don't know what to look for you won't be able to see that... and you cannot make a C-grid by cutting away half of an O-grid! A C-grid has a differently connected topology. Figure 4 on this website shows a C-grid. http://www.aerodyn.org/CFD/Grid/examples.html

 November 3, 2006, 01:23 Re: Grids #6 Charles Guest   Posts: n/a Something to remember with multi-block structured grids, is that the concept of a grid being of O, C or H topology is a bit notional. It is a good description when you mesh with a tool like Icem Hexa, where you can start with a single block topology, which is then split in various ways to match to the geometry. If you are building a grid from the bottom up, i.e. you assemble blocks, it will tend to end up as a topology which can not be characterised as easily.

 November 3, 2006, 08:17 Re: Grids #7 Mani Guest   Posts: n/a ...because the O-C-H nomenclature predates the time when multiblock techniques became popular. They are the main topologies for 2-D single-block grids over simple geometries such as airfoils.

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