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Pressure gradient along a line

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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 11 mai 2011, 11:24 UTC−4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 10 mai 2011, 13:32 UTC−4
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

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Posted: 1 decade ago 11 mai 2011, 05:20 UTC−4
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 11 mai 2011, 10:27 UTC−4
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

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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

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Posted: 1 decade ago 11 mai 2011, 10:43 UTC−4

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 11 mai 2011, 11:24 UTC−4
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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