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-   -   Incylinder Dynamic Mesh Creating Negative Volume (http://www.cfd-online.com/Forums/fluent/41693-incylinder-dynamic-mesh-creating-negative-volume.html)

Sujtih July 12, 2006 21:18

Incylinder Dynamic Mesh Creating Negative Volume
 
Hi, I am Sujith, doing a academic project in Combustion of Diesel Engines. I created the mesh and fed the dynamic mesh parametrs, my starting crank angle is 360, speed is 2100rpm, Crank Step size (deg) is 0.2, Piston Stroke is 118mm and Connecting rod length is 220mm. The Dynamic mesh is moving from TDC to BDC (540deg) and when it is going back, at 641.2 deg, it is creating NEGATIVE VOLUME..!

Can anyone help me by providing informations about this problem and why it is happening?

Please..

Thanks in advance.

Regards, Sujith

Vivek July 20, 2006 16:15

Re: Incylinder Dynamic Mesh Creating Negative Volu
 
After it fails.. display the grid.. usually you could see where the negative volume is located because of gross deformation.

Max July 22, 2006 11:17

Re: Incylinder Dynamic Mesh Creating Negative Volu
 
Hi Sujtih

I am also facing a simillar problem, can you tell me how to fix it?

-Max

Curtis M Schreiber August 1, 2006 15:53

Re: Incylinder Dynamic Mesh Creating Negative Volu
 
Hi, My associate and I encountered a situation similiar to this in an internal combustion engine cycle. The solution(s)for this case were: 1. Start at TDC, so that FLUENT is "creating" cells. 2. Use a structured mesh anywhere where the piston is moving. For our case it was simple to apply a structured mesh since it was just a cylinder, but yours may be different.

CMS


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