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-   -   Movement of piston in a cylinder with fluent? (http://www.cfd-online.com/Forums/ansys/97047-movement-piston-cylinder-fluent.html)

 Whitworth February 7, 2012 20:18

Movement of piston in a cylinder with fluent?

I'm starting to build a model of a piston (say 45mm diameter, 20mm length) in a sealed cylinder of air (50mm diameter 100mm length). This piston moves up and down (+ and minus y) with a sinusoidal velocity.

At the top of the cylinder there is a constant temperature of say 100 degrees centigrade and at the bottom 25 degrees centigrade. As the piston moves downward, the air is forced to the top of the cylinder, heating up and as the piston moves back upward, the air moves back down to the bottom.

My question is, how would I start to go about modeling this in fluent? I've never modelled something with motion before and a tutorial would be great. The setup in my head would be...

-geometry,cylinder of fluid constructed with a missing pocket 45mmx20mm, representing the piston.
-energy equation enabled so heat transfer was active
-no initial fluid velocity (piston would be at bottom dead center)
-top and bottom zones set at constant temperature
-cylinder wall set to 0 heat flux
-viscous model selected depending on approx reynolds number

But where might I find the options to translate the pocket in the continuum?

 Far February 10, 2012 12:03

http://www.cfd-online.com/Forums/ans...ic-engine.html

 rajendra9424 September 18, 2013 09:09

Quote:
 Originally Posted by Whitworth (Post 343234) I'm starting to build a model of a piston (say 45mm diameter, 20mm length) in a sealed cylinder of air (50mm diameter 100mm length). This piston moves up and down (+ and minus y) with a sinusoidal velocity. At the top of the cylinder there is a constant temperature of say 100 degrees centigrade and at the bottom 25 degrees centigrade. As the piston moves downward, the air is forced to the top of the cylinder, heating up and as the piston moves back upward, the air moves back down to the bottom. My question is, how would I start to go about modeling this in fluent? I've never modelled something with motion before and a tutorial would be great. The setup in my head would be... -geometry,cylinder of fluid constructed with a missing pocket 45mmx20mm, representing the piston. -energy equation enabled so heat transfer was active -no initial fluid velocity (piston would be at bottom dead center) -top and bottom zones set at constant temperature -cylinder wall set to 0 heat flux -viscous model selected depending on approx reynolds number But where might I find the options to translate the pocket in the continuum? Thanks in advance :)
Dear Whitworth,

i have also written UDF for moving wall, but the movement of wall is always +y and reaches in original position y=0 but not in -y direction. so how can i make movement of wall in + to - ?

Tutorial : Cold Flow Simulation Inside an SI Engine

Dear Whitworth & rajendra9424

this file can help any one that want to simulate any kind of cylider
with valve motion and injection!
if you need more help
just call me

or here

 mvinovivek March 3, 2015 11:05

I downloaded the file and tried to run the simulation. but after a certain number of iterations i got an access violation error. how can i rectify that. pls help me . Thanks in Advance :) :)