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Pressure gradient along a line

Posted May 10, 2011, 12:27 p.m. EDT Fluid & Heat Version 4.1 5 Replies

Guillermo Vilaplana
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Hi all,

I have a simple 3D flow through a pipe (not perfectly cylindrical) and I would like to print the pressure gradient along a line on the side of my geometry.

Any ideas? it shouldn't be very complicated but I cant do it!

Many thanks
5 Replies Last Post May 11, 2011, 11:24 a.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago May 10, 2011, 1:32 p.m. EDT
Hi

indeed simple (check the doc) or try out:

a) Results add-select a 1D plot group node, add a Line plot, select an edge(s), define your formula plot
b) select the Data Set, add a cut line or an edge data (sub)set node, define its source data set, add a 1D plot group node, select the corresponding line data set, add a line plot node, write your formula and plot

--
Good luck
Ivar
Hi indeed simple (check the doc) or try out: a) Results add-select a 1D plot group node, add a Line plot, select an edge(s), define your formula plot b) select the Data Set, add a cut line or an edge data (sub)set node, define its source data set, add a 1D plot group node, select the corresponding line data set, add a line plot node, write your formula and plot -- Good luck Ivar
Guillermo Vilaplana
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Posted: 1 decade ago May 11, 2011, 5:20 a.m. EDT
Hi Ivar,

I know how to plot a formula along a line, my problem is with the formula : gradient of a scalar field (pressure) along a line in a 3D geometry.

Thanks
Guillermo

Hi Ivar, I know how to plot a formula along a line, my problem is with the formula : gradient of a scalar field (pressure) along a line in a 3D geometry. Thanks Guillermo
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago May 11, 2011, 10:27 a.m. EDT
Hi

Sorry I misunderstood you, well if p is a dependent variable normally px is defined (sometimes pxx second derivative too, depends on the shape element used/selected. Check the COMSOL equations if you see the definition of px,py,pz

--
Good luck
Ivar
Hi Sorry I misunderstood you, well if p is a dependent variable normally px is defined (sometimes pxx second derivative too, depends on the shape element used/selected. Check the COMSOL equations if you see the definition of px,py,pz -- Good luck Ivar
Guillermo Vilaplana
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Posted: 1 decade ago May 11, 2011, 10:43 a.m. EDT

Indeed px, py and pz are defined (well, since its on the boundary I can use dtang() operator).

This is a start, the problem then is to determine the correct direction of the 3D line, wich is complicated to compute manually.

Thanks
Guillermo
Indeed px, py and pz are defined (well, since its on the boundary I can use dtang() operator). This is a start, the problem then is to determine the correct direction of the 3D line, wich is complicated to compute manually. Thanks Guillermo
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago May 11, 2011, 11:24 a.m. EDT
Hi

the edge normal direction are the ...ny,...ny,...nz, or use the boundary coordinates

--
Good luck
Ivar
Hi the edge normal direction are the ...ny,...ny,...nz, or use the boundary coordinates -- Good luck Ivar

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