r</p>
      <p style="font-family: monospace;" class="MsoPlainText">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
V:&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;


        Convection velocity</p>
      <p style="font-family: monospace;" class="MsoPlainText">&nbsp;</p>
      <p style="font-family: monospace;" class="MsoPlainText">A good
        check of convergence can be done by running an isovelocity
        problem with a gaussian pulse.&nbsp; The pulse should, of
        course, be undistorted at the rec