# Movement of piston in a cylinder with fluent?

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 February 7, 2012, 19:18 Movement of piston in a cylinder with fluent? #1 New Member   Andy Join Date: Feb 2012 Posts: 5 Rep Power: 13 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

 February 10, 2012, 11:03 #2 Super Moderator   Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,552 Blog Entries: 6 Rep Power: 53 Check this link http://www.cfd-online.com/Forums/ans...ic-engine.html tsram90 likes this.

September 18, 2013, 09:09
#3
New Member

Rajendra Kumar
Join Date: Jun 2013
Posts: 3
Rep Power: 11
Quote:
 Originally Posted by Whitworth 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 - ?

 September 19, 2013, 12:27 Tutorial : Cold Flow Simulation Inside an SI Engine #4 New Member   Join Date: Mar 2013 Posts: 11 Rep Power: 12 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 download file of Cold Flow Simulation Inside an SI Engine here or here amin_gls likes this.

 March 3, 2015, 10:05 #5 New Member   Vivek M Join Date: Mar 2015 Posts: 2 Rep Power: 0 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

 March 3, 2015, 23:50 Fluent Access Violation error after a specific iteration number #6 New Member   Join Date: Mar 2013 Posts: 11 Rep Power: 12