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August 20, 2007, 07:49 
Confusion abt nonuniform staggered grid

#1 
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Hello,
I'm trying to write a code using SIMPLE on staggered cartesian grids. The books I read mention that u,v,p each are solved on their control volume. However, all the examples are given on uniform grids. What if the grid are nonuniform? If the p nodes are defined on the center of its control volume, is it correct to say that the u nodes will be on the left, right faces of the p control volume? In that case, is the left,right faces of the u control volume on the same location as the p nodes? But if that's the case, u will not be in the center of its own control volume. Or the p nodes do not coincide with the left, right faces of the u control volume and u is at the center of its own control volume. Which one is correct? Or can both be used? Is there any preferred choice? Thank you. 

August 21, 2007, 08:14 
Re: Confusion abt nonuniform staggered grid

#2 
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the type of scheme you apply is important. and you have to use weighted interpolation.


August 29, 2007, 04:46 
Re: Confusion abt nonuniform staggered grid

#3 
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for a 1d problem let's say, two adjacent p control volumes will have lengths delta_x_1 and delta_x_2. the u control volume will thus have length 1/2(delta_x_1 + delta_x_2). is that the confusion? in the program have one delta_x array and subsequently when the delta_x of p cv is required, use that starightway. when the delta_x of the u cv is required, go by the algebra as above. remember delta_x_1/delta_x_2 ratio (larger/smaller) should not exeed 1.2 or so, if delta_x_1 is larger.


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