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-   -   extremely low residuals (http://www.cfd-online.com/Forums/cfx/73294-extremely-low-residuals.html)

ranjith March 4, 2010 00:20

extremely low residuals
 
Hi,
I am doing an FSI simulation of flow through a micro pore(in a tissue engineering cartilage). The problem is that the residuals are very low of the order of 10 raised to -21 and they converge in the first iteration itself. when i view the result I find the velocity also too small of the same order(10 raised to -21) and this isnt what I am expecting.
My simulation setup is as follows - I have a cube made of the scaffold material(youngs modulus .1 MPa) Inside the cube there is spherical pore filled with water with two openings to two sides of the cube. I apply a linear pressure on one face of the cube from 0 to 4000Pa. The opposite face is constrained by a fixed support.
Please help me with this
Ranjith

Lance March 4, 2010 03:24

Hi,
check the dimensions of the fluid and solid domains. I had the same problem when my fluid model was specified in [mm] and my solid in [m], i.e. 1000 times bigger.

Lance

ghorrocks March 4, 2010 06:45

Could also be because you have the units wrong on the driving function. Could also be your timestep is far too small (this is unlikely). But most probably it is a setup error.


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