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I have a problem with plotting a 2D velocity field. I would like to have a plot that shows the velocity in the xy direction at various positions.

The data I have is from a numerical simulation. I have a (virtual) watertank and in that tank are 950 probes that measure the 3 veclocity components, pressure and density (one of the velocity components is zero in an ideal situation).

The output is like this:

V_y V_z V_x pressure density (one files (i.e. one probe) measures on 500 timesteps so I get 500 rows of this format in one file, and that brings me to a total of 950 files with data in this format, but for this purpose I would like to make a plot of one timestep, so one row of each file)

In a separate file are the locations of the probes and are in a format:

y z x

this file has 950 rows of this format (row 1 corresponds to file 1)

I was able to make a plot of the velocities seperatly, but not together and not with arrows (I used contour)

Here are the m-files I am using now (these are for all timesteps)

This is for loading U (x-speed)

________________________________________

U=13.*[sonda(:,3),sonda(:,2)];

for i=50:99

number=num2str(i);

file=strcat('son0',number,'.out');

stored=load( file );

for j=1:500

U((i-49),j+2)=stored(j,4);

end

end

for i=100:999

number=num2str(i);

file=strcat('son',number,'.out');

stored=load( file );

for j=1:500

U((i-49),j+2)=stored(j,4);

end

end

________________________________________

This is for plotting U and saving the plots on my harddisk

________________________________________

x=U(:,1);y=U(:,2);

xmin=min(x); ymin=min(y);

xmax=max(x); ymax=max(y);

xres=200; yres=200;

xv=linspace(xmin, xmax, xres); yv=linspace(ymin, ymax, yres);

[Xinterp,Yinterp]=meshgrid(xv,yv);

for i=1:500

z=U(:,i+2);

Zinterp=griddata(x,y,z,Xinterp,Yinterp);

number=num2str(i);

A=strcat('Perpendicular velocity(U in cm/s) on t=',number);

h=1;

contour(Xinterp,Yinterp,Zinterp,20); title(A);xlabel('Distance to the moving wall'); ylabel('Distance to the bottom');caxis([-0.6 0.6]);

load('Mycolormaps','mycmap');

set(1,'colormap',mycmap);

colorbar('location','eastoutside');

filename=['t',num2str(i+100),'.jpg'];

saveas(h,filename,'jpeg');

end

________________________________________

Could someone please explain how to rearrange my data such that I can use quiver or an other plot function that would serve my purpose? Or if it turns out to be really easy, adjust my m-files so that I can use it? (Please don;t make it too complicated, because creating these m-files is about my level of understanding of matlab).

Thank you in advance,

Ivo

(Sean)

"Ivo " <i.g.s.v.hooijdonk@student.tue.nl> wrote in message <i1er2u$io3$1@fred.mathworks.com>...

> I have a problem with plotting a 2D velocity field. I would like to have a plot that shows the velocity in the xy direction at various positions.

>

> The data I have is from a numerical simulation. I have a (virtual) watertank and in that tank are 950 probes that measure the 3 veclocity components, pressure and density (one of the velocity components is zero in an ideal situation).

> The output is like this:

> V_y V_z V_x pressure density (one files (i.e. one probe) measures on 500 timesteps so I get 500 rows of this format in one file, and that brings me to a total of 950 files with data in this format, but for this purpose I would like to make a plot of one timestep, so one row of each file)

>

> In a separate file are the locations of the probes and are in a format:

> y z x

> this file has 950 rows of this format (row 1 corresponds to file 1)

>

> I was able to make a plot of the velocities seperatly, but not together and not with arrows (I used contour)

>

> Here are the m-files I am using now (these are for all timesteps)

> This is for loading U (x-speed)

> ________________________________________

> U=13.*[sonda(:,3),sonda(:,2)];

> for i=50:99

> number=num2str(i);

> file=strcat('son0',number,'.out');

> stored=load( file );

> for j=1:500

> U((i-49),j+2)=stored(j,4);

> end

> end

> for i=100:999

> number=num2str(i);

> file=strcat('son',number,'.out');

> stored=load( file );

> for j=1:500

> U((i-49),j+2)=stored(j,4);

> end

> end

> ________________________________________

> This is for plotting U and saving the plots on my harddisk

> ________________________________________

> x=U(:,1);y=U(:,2);

> xmin=min(x); ymin=min(y);

> xmax=max(x); ymax=max(y);

>

> xres=200; yres=200;

>

> xv=linspace(xmin, xmax, xres); yv=linspace(ymin, ymax, yres);

>

> [Xinterp,Yinterp]=meshgrid(xv,yv);

> for i=1:500

> z=U(:,i+2);

> Zinterp=griddata(x,y,z,Xinterp,Yinterp);

> number=num2str(i);

> A=strcat('Perpendicular velocity(U in cm/s) on t=',number);

> h=1;

> contour(Xinterp,Yinterp,Zinterp,20); title(A);xlabel('Distance to the moving wall'); ylabel('Distance to the bottom');caxis([-0.6 0.6]);

> load('Mycolormaps','mycmap');

> set(1,'colormap',mycmap);

> colorbar('location','eastoutside');

> filename=['t',num2str(i+100),'.jpg'];

> saveas(h,filename,'jpeg');

> end

> ________________________________________

>

> Could someone please explain how to rearrange my data such that I can use quiver or an other plot function that would serve my purpose? Or if it turns out to be really easy, adjust my m-files so that I can use it? (Please don;t make it too complicated, because creating these m-files is about my level of understanding of matlab).

>

> Thank you in advance,

>

> Ivo

If my understanding of what you have is correct:

>>quiver(Xinterp(:),Yinterp(:),U(:,1),U(:,2)); %The colon operator turns the matrix into a vector taking pieces column-wise.

%Thus what I'm doing is making 4 column vectors: x-coords, y-coords, U-coords, V-coords and quiver() will draw an arrow for each row of the 4.

(Sean)

> I have a problem with plotting a 2D velocity field. I would like to have a plot that shows the velocity in the xy direction at various positions.

>

> The data I have is from a numerical simulation. I have a (virtual) watertank and in that tank are 950 probes that measure the 3 veclocity components, pressure and density (one of the velocity components is zero in an ideal situation).

> The output is like this:

> V_y V_z V_x pressure density (one files (i.e. one probe) measures on 500 timesteps so I get 500 rows of this format in one file, and that brings me to a total of 950 files with data in this format, but for this purpose I would like to make a plot of one timestep, so one row of each file)

>

> In a separate file are the locations of the probes and are in a format:

> y z x

> this file has 950 rows of this format (row 1 corresponds to file 1)

>

> I was able to make a plot of the velocities seperatly, but not together and not with arrows (I used contour)

>

> Here are the m-files I am using now (these are for all timesteps)

> This is for loading U (x-speed)

> ________________________________________

> U=13.*[sonda(:,3),sonda(:,2)];

> for i=50:99

> number=num2str(i);

> file=strcat('son0',number,'.out');

> stored=load( file );

> for j=1:500

> U((i-49),j+2)=stored(j,4);

> end

> end

> for i=100:999

> number=num2str(i);

> file=strcat('son',number,'.out');

> stored=load( file );

> for j=1:500

> U((i-49),j+2)=stored(j,4);

> end

> end

> ________________________________________

> This is for plotting U and saving the plots on my harddisk

> ________________________________________

> x=U(:,1);y=U(:,2);

> xmin=min(x); ymin=min(y);

> xmax=max(x); ymax=max(y);

>

> xres=200; yres=200;

>

> xv=linspace(xmin, xmax, xres); yv=linspace(ymin, ymax, yres);

>

> [Xinterp,Yinterp]=meshgrid(xv,yv);

> for i=1:500

> z=U(:,i+2);

> Zinterp=griddata(x,y,z,Xinterp,Yinterp);

> number=num2str(i);

> A=strcat('Perpendicular velocity(U in cm/s) on t=',number);

> h=1;

> contour(Xinterp,Yinterp,Zinterp,20); title(A);xlabel('Distance to the moving wall'); ylabel('Distance to the bottom');caxis([-0.6 0.6]);

> load('Mycolormaps','mycmap');

> set(1,'colormap',mycmap);

> colorbar('location','eastoutside');

> filename=['t',num2str(i+100),'.jpg'];

> saveas(h,filename,'jpeg');

> end

> ________________________________________

>

> Could someone please explain how to rearrange my data such that I can use quiver or an other plot function that would serve my purpose? Or if it turns out to be really easy, adjust my m-files so that I can use it? (Please don;t make it too complicated, because creating these m-files is about my level of understanding of matlab).

>

> Thank you in advance,

>

> Ivo

If my understanding of what you have is correct:

>>quiver(Xinterp(:),Yinterp(:),U(:,1),U(:,2)); %The colon operator turns the matrix into a vector taking pieces column-wise.

%Thus what I'm doing is making 4 column vectors: x-coords, y-coords, U-coords, V-coords and quiver() will draw an arrow for each row of the 4.

"Sean " <sean.dewolski@nospamplease.umit.maine.edu> wrote in message <i1f2qc$4t5$1@fred.mathworks.com>...

> "Ivo " <i.g.s.v.hooijdonk@student.tue.nl> wrote in message <i1er2u$io3$1@fred.mathworks.com>...

> > I have a problem with plotting a 2D velocity field. I would like to have a plot that shows the velocity in the xy direction at various positions.

> >

> > The data I have is from a numerical simulation. I have a (virtual) watertank and in that tank are 950 probes that measure the 3 veclocity components, pressure and density (one of the velocity components is zero in an ideal situation).

> > The output is like this:

> > V_y V_z V_x pressure density (one files (i.e. one probe) measures on 500 timesteps so I get 500 rows of this format in one file, and that brings me to a total of 950 files with data in this format, but for this purpose I would like to make a plot of one timestep, so one row of each file)

> >

> > In a separate file are the locations of the probes and are in a format:

> > y z x

> > this file has 950 rows of this format (row 1 corresponds to file 1)

> >

> > I was able to make a plot of the velocities seperatly, but not together and not with arrows (I used contour)

> >

> > Here are the m-files I am using now (these are for all timesteps)

> > This is for loading U (x-speed)

> > ________________________________________

> > U=13.*[sonda(:,3),sonda(:,2)];

> > for i=50:99

> > number=num2str(i);

> > file=strcat('son0',number,'.out');

> > stored=load( file );

> > for j=1:500

> > U((i-49),j+2)=stored(j,4);

> > end

> > end

> > for i=100:999

> > number=num2str(i);

> > file=strcat('son',number,'.out');

> > stored=load( file );

> > for j=1:500

> > U((i-49),j+2)=stored(j,4);

> > end

> > end

> > ________________________________________

> > This is for plotting U and saving the plots on my harddisk

> > ________________________________________

> > x=U(:,1);y=U(:,2);

> > xmin=min(x); ymin=min(y);

> > xmax=max(x); ymax=max(y);

> >

> > xres=200; yres=200;

> >

> > xv=linspace(xmin, xmax, xres); yv=linspace(ymin, ymax, yres);

> >

> > [Xinterp,Yinterp]=meshgrid(xv,yv);

> > for i=1:500

> > z=U(:,i+2);

> > Zinterp=griddata(x,y,z,Xinterp,Yinterp);

> > number=num2str(i);

> > A=strcat('Perpendicular velocity(U in cm/s) on t=',number);

> > h=1;

> > contour(Xinterp,Yinterp,Zinterp,20); title(A);xlabel('Distance to the moving wall'); ylabel('Distance to the bottom');caxis([-0.6 0.6]);

> > load('Mycolormaps','mycmap');

> > set(1,'colormap',mycmap);

> > colorbar('location','eastoutside');

> > filename=['t',num2str(i+100),'.jpg'];

> > saveas(h,filename,'jpeg');

> > end

> > ________________________________________

> >

> > Could someone please explain how to rearrange my data such that I can use quiver or an other plot function that would serve my purpose? Or if it turns out to be really easy, adjust my m-files so that I can use it? (Please don;t make it too complicated, because creating these m-files is about my level of understanding of matlab).

> >

> > Thank you in advance,

> >

> > Ivo

>

>

> If my understanding of what you have is correct:

> >>quiver(Xinterp(:),Yinterp(:),U(:,1),U(:,2)); %The colon operator turns the matrix into a vector taking pieces column-wise.

> %Thus what I'm doing is making 4 column vectors: x-coords, y-coords, U-coords, V-coords and quiver() will draw an arrow for each row of the 4.

Thank you. i don't really understand why I didn't get it right before. I have been spending quitte some time on solving this. But now it works.

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