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How to "Arrow Plot" without its magnitude

Posted 18.05.2017, 00:46 GMT-4 5 Replies

NDN UNIST/Mechanical Engineering
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Hi all
I am newbie in COMSOL,
When I used "Electrostatic Module" to solve Laplace's equation, I need to visualize the Electrical field by arrow, just direction, no need to magnitude
I tried to plot by Arrow Surface but I can not find any option to disable the magnitude of arrow.

Does anyone have ideas for my case ? Plz help me

Thanks in advanced.
5 Replies Last Post 18.05.2017, 02:24 GMT-4
Mohammad Amin Kazemi
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Posted: 8 years ago 18.05.2017, 01:33 GMT-4
Updated: 8 years ago 18.05.2017, 01:47 GMT-4
Hi,

If you are using 3D Cartesian coordinate, you may get your desired arrow surface plot as follows:

set the x component: x component/magnitude of the vector
set the y component: y component/magnitude of the vector
set the z component: z component/magnitude of the vector

For example,

For velocity field:
x component: u/sqrt(u^2+v^2+w^2)
y component: v/sqrt(u^2+v^2+w^2)
z component: w/sqrt(u^2+v^2+w^2)

For electrical field:
x component: ec.Ex/sqrt(ec.Ex^2+ec.Ey^2+ec.Ez^2)
y component: ec.Ey/sqrt(ec.Ex^2+ec.Ey^2+ec.Ez^2)
z component: ec.Ez/sqrt(ec.Ex^2+ec.Ey^2+ec.Ez^2)

For polar coordinates, the formula is different.
Of course, there should be other ways as well. but this is what I'd do.

Amin,
Hi, If you are using 3D Cartesian coordinate, you may get your desired arrow surface plot as follows: set the x component: x component/magnitude of the vector set the y component: y component/magnitude of the vector set the z component: z component/magnitude of the vector For example, For velocity field: x component: u/sqrt(u^2+v^2+w^2) y component: v/sqrt(u^2+v^2+w^2) z component: w/sqrt(u^2+v^2+w^2) For electrical field: x component: ec.Ex/sqrt(ec.Ex^2+ec.Ey^2+ec.Ez^2) y component: ec.Ey/sqrt(ec.Ex^2+ec.Ey^2+ec.Ez^2) z component: ec.Ez/sqrt(ec.Ex^2+ec.Ey^2+ec.Ez^2) For polar coordinates, the formula is different. Of course, there should be other ways as well. but this is what I'd do. Amin,
NDN UNIST/Mechanical Engineering
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Posted: 8 years ago 18.05.2017, 01:47 GMT-4
Thanks so much Mohammad Amin Kazemi !

I've done by following your instructions.
Thanks so much Mohammad Amin Kazemi ! I've done by following your instructions.
Gunnar Andersson COMSOL Employee

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Posted: 8 years ago 18.05.2017, 02:12 GMT-4

I am newbie in COMSOL,
When I used "Electrostatic Module" to solve Laplace's equation, I need to visualize the Electrical field by arrow, just direction, no need to magnitude
I tried to plot by Arrow Surface but I can not find any option to disable the magnitude of arrow.


The Coloring and Style section in the Arrow plots contains an Arrow length drop-down menu. Set it to Normalized.


[QUOTE] I am newbie in COMSOL, When I used "Electrostatic Module" to solve Laplace's equation, I need to visualize the Electrical field by arrow, just direction, no need to magnitude I tried to plot by Arrow Surface but I can not find any option to disable the magnitude of arrow. [/QUOTE] The Coloring and Style section in the Arrow plots contains an Arrow length drop-down menu. Set it to Normalized.
NDN UNIST/Mechanical Engineering
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Posted: 8 years ago 18.05.2017, 02:21 GMT-4
Thanks very much Gunnar Andersson

I've also done by your direction.
But I saw that all arrows is same colour. So how can I setup the colour scale for arrows corresponding to their magnitude ? I mean that the arrows will help me to visualize the magnitude via colour scale while the length of them is uniform.

P/S: In box " Colour and Style", I did see any option like " Rainbow"

Thanks in advance
Thanks very much Gunnar Andersson I've also done by your direction. But I saw that all arrows is same colour. So how can I setup the colour scale for arrows corresponding to their magnitude ? I mean that the arrows will help me to visualize the magnitude via colour scale while the length of them is uniform. P/S: In box " Colour and Style", I did see any option like " Rainbow" Thanks in advance
Gunnar Andersson COMSOL Employee

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Posted: 8 years ago 18.05.2017, 02:24 GMT-4

I've also done by your direction.
But I saw that all arrows is same colour. So how can I setup the colour scale for arrows corresponding to their magnitude ? I mean that the arrows will help me to visualize the magnitude via colour scale while the length of them is uniform.


Right-click on the arrow plot and select Color Expression. This adds a subnode where you can define the expression for the arrow color. You can also choose what color table to use.

[QUOTE] I've also done by your direction. But I saw that all arrows is same colour. So how can I setup the colour scale for arrows corresponding to their magnitude ? I mean that the arrows will help me to visualize the magnitude via colour scale while the length of them is uniform. [/QUOTE] Right-click on the arrow plot and select Color Expression. This adds a subnode where you can define the expression for the arrow color. You can also choose what color table to use.

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