CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > ANSYS > FLUENT

2D piston in steady closed pipe flow BC query!

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Search this Thread Display Modes
Old   April 10, 2014, 10:25
Default 2D piston in steady closed pipe flow BC query!
New Member
Lisa Marfell
Join Date: Nov 2013
Posts: 7
Rep Power: 11
lmarf88 is on a distinguished road

I am trying to model a 2D creviced piston in a rapid compression machine. As the fluid stays within the cylinder, the flow is a closed system. My aim is to analyse the flow field around the piston, looking particularly at pressure/ temperature changes.

Due to platform issues, I am unable to use dynamic meshing or user-defined functions to simulate the movement of a piston. Therefore I am limited to steady flow and a moving wall boundary condition.

The wall is moving toward the end of the cylinder, thus "compressing" the fluid. I am struggling finding the correct boundary conditions and was wondering if anybody might be able to help.

Originally I had a velocity inlet of 10m/s at the piston seal, simulating the seal pushing fluid out into the main chamber as the piston moves towards the cylinder end (moving wall boundary condition also set to 10m/s). The visulations of the flow field contain vortices and what I might expect to happen in real life. However I was recommended that this wasn't particularly realistic to the practical boundary conditions.

I was advised that it would be more appropriate to not have an inlet, but to have a mass flow outlet at the seal of the piston (provided the seal leaks slightly), would a pressure-outlet be more suitable? If I have no inlet and a pressure outlet, should I be using target mass flow rate in the pressure outlet boundary condition? the flow field visulation I get from pressure pathlines shows a vortex in the main pipe and also in the crevices, but there is no pressure distribution in the main section.

I am confused which boundary conditions would be most appropriate for my application.

Any help would be extremely useful!


Last edited by lmarf88; April 10, 2014 at 13:08.
lmarf88 is offline   Reply With Quote


boundary conditions, piston, rapid compression machine

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
Laminar , steady state pipe flow andesameer OpenFOAM 31 March 3, 2015 02:42
setup problems - LES pipe flow with cyclic BC (1) and direct mapped inlet (2) florian_krause OpenFOAM 22 June 13, 2013 21:25
flow in perforated pipe distributor pertupd ANSYS 0 August 12, 2009 08:36
Reverse Flow at Rotating Pipe Outlet vismech STAR-CCM+ 1 August 11, 2009 10:38
About Turbulence Intensity (Pipe flow assimilated) gRomK13 Main CFD Forum 1 July 10, 2009 03:11

All times are GMT -4. The time now is 19:13.