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-   -   gravity problem. (http://www.cfd-online.com/Forums/fluent/38397-gravity-problem.html)

vidhuresh October 27, 2005 03:48

gravity problem.
 
hi i am solving simple one dimensional problem of flow through pipe with velocityinlet and pressure outlet boundary conditions. axis of pipe is x-positive direction.

i could not finding the effect of gravity in solution (pressureplots) when i am activating gravity in opertion condition panel with value9.81.

whether in static pressure plot/ total pressure plot i find efect of gravity.


aykut October 27, 2005 06:42

Re: gravity problem.
 
Hi are u making an air flow simulation or something else? Regards

vidhuresh October 28, 2005 01:14

Re: gravity problem.
 
hi,

i am simulating with water. i have even changed the sign of gravity as well but no change in result .

Matt Frain October 28, 2005 12:08

Re: gravity problem.
 
Try setting the operating density to zero.

Matt Frain October 29, 2005 21:42

Re: gravity problem.
 
Some things to consider:

1) If gravity is acting in the -Y direction in this case, gravity will only cause a hydrostatic pressure gradient across the pipe diameter. It will not affect the flow field unless the fluid density varies.

2) If your pipe diameter is small and the fluid is a gas, the hydrostatic pressure gradient will be negligibly small as compared to the pressure gradient due to flow resistance. If this is the case, then you will not see this gradient on a contour plot. The effect you are seeking may be very small compared to other flow gradients.


vidhuresh October 30, 2005 08:25

Re: gravity problem.
 
hi mattfrain,

i have checked it again my gravity in x-direction. fluid i am using is water. pipe diameter is 10 cm and lengthis 1m. velocity at inlet is 0.001m/s, pressuer at outlet is 0. if there is any another method please help me .

thanks for your reply.


vidhuresh October 31, 2005 01:59

Re: gravity problem.
 
hi matt frain,

you are right. setting operating density to zero is giving results

thanks for your reply

bye-bye


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