VELOCITY_ARROWS_SEQUENCE2
Velocity Field Arrow Sequence

VELOCITY_ARROWS_SEQUENCE2 is a MATLAB program which makes velocity field arrow plots using a sequence of files, each of which stores the X and Y coordinates, and U and V velocity components, at a set of nodes, stored as TABLE files (except that no "#" comment lines are allowed).

The program is mainly a preprocessor for MATLAB's quiver routine. It reads the (X,Y) coordinates and horizontal and vertical velocities from an "XYUV" file. It computes the maximum velocity magnitude over all datasets, so that there is a single velocity scale.

It then makes a few settings, calls quiver to plot the arrows, and also traces out the convex hull of the points, which is presumably the boundary of the region. The resulting image is displayed, and saved to a PNG file.

In addition, the program assumes that the user actually has a sequence of XYUV datasets, with "consecutive" names, each of which is to be plotted. The program automatically reads each such dataset and creates the sequence of PNG files. It is easy to take such a sequence and make an animation.

Licensing:

The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.

Related Data and Programs:

VECTOR_MAGNITUDE_GRID, a MATLAB program which reads node and velocity data from a file, and using an interpolating function, is able to display a contour plot of the vector magnitude field.

VECTOR_PLOT, a FORTRAN90 program which can read an XY file and a UV file and plot the velocity and velocity direction fields.

VECTOR_STREAM_GRID, a MATLAB program which reads node and vector data from a file, computes an interpolatory function, evaluates on a uniform grid of points specified by the user, and displays a streamline plot of the vector field.

VELOCITY_ARROWS, a MATLAB program which plots a velocity vector field.

VELOCITY_ARROWS_GRID, a MATLAB program which reads files of node and velocity data, and, using interpolation, creates a vector plot with arrows place on a uniform grid of the user's specification.

VELOCITY_ARROWS_SEQUENCE, a MATLAB program which handles the case where a single XY file is used (fixed geometry), along with a sequence of files containing UV values.)

Source Code:

• velocity_arrows_sequence2.m, the source code;
• file_exist.m, is true if a file exists;
• file_name_ext_swap.m, changes the extension on a file name;
• file_name_inc.m, increments a file name;
• timestamp.m, prints the YMDHMS date as a timestamp;

Examples and Tests:

INOUT is defined by the following data, for which the XY coordinates do not change:

• inout_xyuv001.txt, a set of coordinate and velocity data.
• inout_xyuv002.txt, a set of coordinate and velocity data.
• inout_xyuv003.txt, a set of coordinate and velocity data.
• inout_xyuv004.txt, a set of coordinate and velocity data.
• inout_xyuv005.txt, a set of coordinate and velocity data.
• inout_xyuv006.txt, a set of coordinate and velocity data.
• inout_xyuv007.txt, a set of coordinate and velocity data.
• inout_xyuv008.txt, a set of coordinate and velocity data.

The command

velocity_arrows_sequence2 ( 'inout_xyuv001.txt', 3.0 )

• inout_xyuv001.png, a plot of velocity direction data.
• inout_xyuv002.png, a plot of velocity direction data.
• inout_xyuv003.png, a plot of velocity direction data.
• inout_xyuv004.png, a plot of velocity direction data.
• inout_xyuv005.png, a plot of velocity direction data.
• inout_xyuv006.png, a plot of velocity direction data.
• inout_xyuv007.png, a plot of velocity direction data.
• inout_xyuv008.png, a plot of velocity direction data.

CHANNEL is defined by the following data, for which the XY coordinates DOES change. This is an interesting demonstration, since the nodes seem to move with the flow.

• channel_xyuv001.txt, a set of coordinate and velocity data.
• channel_xyuv002.txt, a set of coordinate and velocity data.
• channel_xyuv003.txt, a set of coordinate and velocity data.
• channel_xyuv004.txt, a set of coordinate and velocity data.
• channel_xyuv005.txt, a set of coordinate and velocity data.
• channel_xyuv006.txt, a set of coordinate and velocity data.
• channel_xyuv007.txt, a set of coordinate and velocity data.
• channel_xyuv008.txt, a set of coordinate and velocity data.
• channel_xyuv009.txt, a set of coordinate and velocity data.
• channel_xyuv010.txt, a set of coordinate and velocity data.
• channel_xyuv011.txt, a set of coordinate and velocity data.
• channel_xyuv012.txt, a set of coordinate and velocity data.
• channel_xyuv013.txt, a set of coordinate and velocity data.
• channel_xyuv014.txt, a set of coordinate and velocity data.
• channel_xyuv015.txt, a set of coordinate and velocity data.
• channel_xyuv016.txt, a set of coordinate and velocity data.

The command

velocity_arrows_sequence2 ( 'channel_xyuv001.txt', 0.10 )

• channel_xyuv001.png, a plot of velocity direction data.
• channel_xyuv002.png, a plot of velocity direction data.
• channel_xyuv003.png, a plot of velocity direction data.
• channel_xyuv004.png, a plot of velocity direction data.
• channel_xyuv005.png, a plot of velocity direction data.
• channel_xyuv006.png, a plot of velocity direction data.
• channel_xyuv007.png, a plot of velocity direction data.
• channel_xyuv008.png, a plot of velocity direction data.
• channel_xyuv009.png, a plot of velocity direction data.
• channel_xyuv010.png, a plot of velocity direction data.
• channel_xyuv011.png, a plot of velocity direction data.
• channel_xyuv012.png, a plot of velocity direction data.
• channel_xyuv013.png, a plot of velocity direction data.
• channel_xyuv014.png, a plot of velocity direction data.
• channel_xyuv015.png, a plot of velocity direction data.
• channel_xyuv016.png, a plot of velocity direction data.

You can go up one level to the MATLAB source codes.