# error estimation for grid independence

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

 October 14, 2001, 05:05 error estimation for grid independence #1 santosh Guest   Posts: n/a hi, I want to know if fluent has any capability to measure the error using the x-y plot which contains two curves say pressure distribution curves. If the answer is no,can anybody tell me if there are any tools/softwares available to do this and also if it is available on the net. thanks and regards, santosh

 October 16, 2001, 06:11 Re: error estimation for grid independence #2 dimitris Guest   Posts: n/a No, to my knowledge, Fluent does not have such an error analysis option. What you can do is write (in the "Plot/XY plot" panel, check "write to file" box) the two curves, i.e. get 2 ascii files containing 2 columns each (e.g. distance vs pressure_gradient) and read them in a spreadsheet (e.g. Excel). Then you can do further post-processing in order to calculate the error between the two runs.

 October 16, 2001, 07:25 Re: error estimation for grid independence #3 santosh Guest   Posts: n/a thank u for the reply,dimitris. one more thing,may sound silly,since the grid resolution is different for the two xy files the vector size will be different.How can I calculate the error between two different size vectors? thanks and regards, santosh

 October 17, 2001, 16:06 Re: error estimation for grid independence #4 dimitris Guest   Posts: n/a If the geometry is the same in both meshes you will have two curves (in XY plot) starting and ending at the same x values but with different number and distribution of points. Now there are two solutions: 1. You calculate a fit for both of them (e.g. of a polynomial form in Excel or in another data handling program) and from their analytical form calculate the error at certain x values of your choice. 2. For certain x values of your choice interpolate (say a linearly) from the two neighbouring values in order to find the y value at that point for both results. Then find the relative error. for example you may have these 2 data sets: set 1 set 2 x y x y 1.1 3.4 0.98 3.6 2.1 4.5 1.3 4.1 3.1 4.4 2.5 4.6 so if you want to find the error in x=2 you interpolate between points 1 & 2 for dataset 1 and between points 2 & 3 of dataset 2. You find the two interpolated values and then find the error in x=2.

 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 nickninevah Main CFD Forum 6 October 15, 2010 17:25 lucifer FLUENT 0 December 14, 2009 20:59 Shane Schouten FLUENT 0 October 11, 2006 16:50 Mattis Voss FLUENT 1 November 23, 2005 11:30 G.Balakrishnan FLUENT 4 November 21, 2000 12:05

All times are GMT -4. The time now is 22:33.