# Density in icoFoam Densidad en icoFoam

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

 August 23, 2006, 12:47 Hi, Thanks in advance . i #1 New Member   Manuel Felipe Mejia De Alba Join Date: Mar 2009 Posts: 10 Rep Power: 9 Hi, Thanks in advance . i try to run a nozzle model, very simple, using icofoam. After try and try, and try ;-), run without problems. I run the same model in ANSYS and the result are not equal. In ansys, i need the density, but in IcoFoam No. what equations solved icofoam, where not is necesary the density.?? My model is a modifid cavity, whit the nu 0.01. thanks. ________________ Hola Gracias por adelantado. yo estoy tratando de correr un modelo de una tobera sencilla. Despues de tratat y tratar, logre que corriera sin problemas. Yo tratto de correr el mismo ejemplo en Ansys, pero el resultado no es el mismo. Ademas en ansys es necesario la densidad pero en icofoam no. Que ecuaciones resuelve icofoam, donde no es necesario la densidad? Mi modelo es como el modelo cavity pero modificado, con nu de 0.01 Gracias Manuel F. Mejia De Alba Universidad Nacional de Colombia.

 August 23, 2006, 13:41 In icoFoam, the pressure being #2 Senior Member   Gavin Tabor Join Date: Mar 2009 Posts: 181 Rep Power: 9 In icoFoam, the pressure being solved is not the true pressure but is in fact p/rho. Thus the density cancels out throughout. Gavin

 August 24, 2006, 16:50 Hi Ok, the press is equal. #3 New Member   Manuel Felipe Mejia De Alba Join Date: Mar 2009 Posts: 10 Rep Power: 9 Hi Ok, the press is equal. But, what happend whit the velocity, the graphics change, when change the density. how i do, for make a model with the density of any value. thanks

 August 24, 2006, 17:00 Multiply the pressure field wi #4 Senior Member   Hrvoje Jasak Join Date: Mar 2009 Location: London, England Posts: 1,784 Rep Power: 22 Multiply the pressure field with the value of density. If you want to feel really good about it, you can also add it an offset, e.g. 101325 Pascal for air at atmospheric conditions. This can all be done after the simulation and there's no need to change the solver. Look at the magU utility for examples - you will be manipulating the pressure instead. Hrv __________________ Hrvoje Jasak Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk

 August 24, 2006, 17:37 ok, with the press, i not have #5 New Member   Manuel Felipe Mejia De Alba Join Date: Mar 2009 Posts: 10 Rep Power: 9 ok, with the press, i not have problems my doubts are with the velocity field: this is independent of density?? thanks and sorry the insistence. Manuel.

 August 25, 2006, 07:26 Velocity is fine: remember, yo #6 Senior Member   Hrvoje Jasak Join Date: Mar 2009 Location: London, England Posts: 1,784 Rep Power: 22 Velocity is fine: remember, you only have grad p in the momentum equation and that does not change for arbitrary offset of p. Enjoy, Hrv __________________ Hrvoje Jasak Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk

 August 26, 2006, 12:35 Hi again, and I am sorry for i #7 New Member   Manuel Felipe Mejia De Alba Join Date: Mar 2009 Posts: 10 Rep Power: 9 Hi again, and I am sorry for inconvenients for so many questions. One more, when I`m looking in the icofoam solver code, it appears a phi term (like a field Phi), that is multiply for velocity, and I`m not sure if that term is related with viscous loss term of generalized momentum equation. The problem is that changes in the kinematic viscosity produces big changes in the velocity field pattern, and not only in velocity field values. Thanks again

 August 26, 2006, 12:42 Hi again, and I am sorry for i #8 New Member   Manuel Felipe Mejia De Alba Join Date: Mar 2009 Posts: 10 Rep Power: 9 Hi again, and I am sorry for inconvenients for so many questions. One more, when I`m looking in the icofoam solver code, it appears a phi term (like a field Phi), that is multiply for velocity, and I`m not sure if that term is related with viscous loss term of generalized momentum equation. The problem is that changes in the kinematic viscosity produces big changes in the velocity field pattern, and not only in velocity field values.

 September 22, 2010, 04:10 #9 Senior Member   Pavan Join Date: May 2009 Location: Melbourne Posts: 101 Rep Power: 9 Yeah but when you change viscosity you're changing Reynolds number so you should expect a change in flow field. Also if I'm not mistaken, Phi is a scaled flux per unit density per unit area...?

 Thread Tools Display Modes Linear Mode

 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 OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post aap OpenFOAM Running, Solving & CFD 15 May 28, 2012 08:30 kar OpenFOAM Running, Solving & CFD 3 February 20, 2008 06:20 msrinath80 OpenFOAM Bugs 6 November 19, 2007 18:35 gruber2 OpenFOAM Running, Solving & CFD 3 April 3, 2007 06:26 ds2taieb OpenFOAM Installation 1 March 24, 2006 04:22

All times are GMT -4. The time now is 12:38.