# Volume or Weight ratio in modelling Air?

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

 August 16, 2013, 09:40 Volume or Weight ratio in modelling Air? #1 Senior Member     Ehsan Join Date: Oct 2012 Location: Iran Posts: 2,210 Rep Power: 19 Sponsored Links in the constant folder I have set Air coefficients for JANAF thermoType from averaging air components.but have a doubt,I have set coefficients according to 75% N2 and 25% O2 as my adviser proposed,but I want to be more accurate, is averaging based on weights more precise or based on volumes? in what extent its important?is it necessary to change the approximate coefficients? http://www.engineeringtoolbox.com/ai...ion-d_212.html __________________ Injustice Anywhere is a Threat for Justice Everywhere.Martin Luther King. To Be or Not To Be,Thats the Question! The Only Stupid Question Is the One that Goes Unasked.

 August 31, 2013, 12:32 #2 Super Moderator   Bruno Santos Join Date: Mar 2009 Location: Lisbon, Portugal Posts: 9,978 Blog Entries: 39 Rep Power: 108 Hi Ehsan, Do you mind providing more information? Namely how did you exactly define those values of 75% vs 25%? Best regards, Bruno __________________ OpenFOAM: FAQ | Getting started Forum: How to get help, to post code/output and forum guide What am I doing/planning: blog/wiki Read this before sending me PM

 August 31, 2013, 14:39 #3 Senior Member     Ehsan Join Date: Oct 2012 Location: Iran Posts: 2,210 Rep Power: 19 Hi Bruno I have multiplyed the JANAF coefficients(7 numbers) of nitrogen to .75 and for oxygen have multiplied them to .25 and then added them together,isn't it correct? the answers look fine but I want to know is this numbers accurate enough? __________________ Injustice Anywhere is a Threat for Justice Everywhere.Martin Luther King. To Be or Not To Be,Thats the Question! The Only Stupid Question Is the One that Goes Unasked.

 August 31, 2013, 14:50 #4 Super Moderator   Bruno Santos Join Date: Mar 2009 Location: Lisbon, Portugal Posts: 9,978 Blog Entries: 39 Rep Power: 108 Hi Ehsan, OK, still not enough information. So I ask in more detail: How exactly did you do the math?No need to specify all of the coefficient values, "a0, a1" and so on is enough. And what results did you get? And in comparison with the values used in the dictionary file, what values were you using before and are using now? Best regards, Bruno __________________ OpenFOAM: FAQ | Getting started Forum: How to get help, to post code/output and forum guide What am I doing/planning: blog/wiki Read this before sending me PM

 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 bobburnquist OpenFOAM Native Meshers: snappyHexMesh and Others 6 August 26, 2015 09:38 dan86 FLUENT 0 July 19, 2013 11:23 alcesalces FLOW-3D 5 August 28, 2009 17:04 alcesalces Main CFD Forum 0 August 19, 2009 14:33 Jack CFX 0 August 20, 2004 01:04