Pointwise - Converting 2D Plot3d grid files to 2D Plot2d

Introduction

I was trying to use Pointwise to generate Plot2d grids, and I discovered that Pointwise appears to be only capable of generating Plot3d grids.  I couldn't find a solution inside of Pointwise so I wrote the Matlab script below to address it.

A quick explanation on the difference between 2D-Plot3d and 2D-Plot2D grids.  When generating a 2D grid in Pointwise, the program outputs a z-coordinate for each point (which is always 0).  Here's an example of the difference between the 2D-Plot3d and 2D-Plot2d grid file:

2D-Plot3d

2

30 30 1

59 30 1

...xdata(block 1)...

...ydata(block 1)...

...zdata(block 1) = 0...

...xdata(block 2)...

...ydata(block 2)...

...zdata(block 2) = 0...

2D-Plot2d

2

30 30

59 30

...xdata(block 1)...

...ydata(block 1)...

...xdata(block 2)...

...ydata(block 2)...

Why does this matter?  

First, Vulcan doesn't care.  When importing the grid file into vulcanig, the user can specify if it is a Plot3D or Plot2D file, and Vulcan will take care of it.

However, TecPlot DOES care.  Because the output of vulcan is in a true 2D format, TecPlot cannot plot the solution against the 2D-Plot3D grid.  It needs the 2D-Plot2D grid.  

The code

The following code is written in MATLAB

clc; close all; clear all;

%% input

inputFile=['C:\Users\John\Documents\PointwiseExample','\','expansionChamber.x'];

outputFile='grid.x';

%% read in 2D(x=m,y=n,z=1) data

A0 = importdata(inputFile);  %raw data

A=A0;  %raw data to be trucated

% number of blocks in data

numBlocks=A(1);

% grab matrix sizes from the header

for i = 1:numBlocks

    m(i)=A(2+(i-1)*3);

    n(i)=A(3+(i-1)*3);

end

% throw away header info from A

A=A(2+numBlocks*3:end);

% grab x and y data from A and ignore z

for i = 1:numBlocks

    N=m(i)*n(i);

    x{i}=A(1:N);

    A=A(N+1:end);

    y{i}=A(1:N);

    A=A(N+1:end);

    A=A(N+1:end); %delete z

end

%% plot data

figure; hold on

colors=['brkg'];

for i = 1:numBlocks

    plot(x{i},y{i},[colors(i),'+'])

end

%% write 2D(x=m,y=n) data (with the single z value stripped out)

fileID = fopen(outputFile,'w');

% write number of blocks

fprintf(fileID,[num2str(numBlocks) '\r\n']);

% write matrix sizes for each block

for i = 1:numBlocks

    fprintf(fileID,[num2str(m(i)), '\t', num2str(n(i)), '\r\n']);

end

% write x and y data for each block

for i = 1:numBlocks

    p=x{i};

    for k=1:2

        if k==1

            p=x{i};

        else

            p=y{i};

        end

        

        while(length(p)>=4)

    %         fprintf(fileID,[num2str(p(1)), '\t', num2str(p(2)), '\t', num2str(p(3)), '\t',num2str(p(4)), '\r\n']);

            fprintf(fileID,'%1.15e\t%1.15e\t%1.15e\t%1.15e\r\n',p(1),p(2),p(3),p(4));

            p=p(5:end);

        end

        if p~=0

            for j=1:length(p)

                fprintf(fileID,'%1.15e\t', p(j));

            end

            fprintf(fileID,'\r\n');

        end

    

    end

end