bht_ellipse page

Biohydrodynamics Toolbox    

bht_ellipse

Define an ellipse-shaped boundary.

Syntax

y = bht_ellipse(t,der,settings)

Description

This function is used to define an ellipse-shaped boundary as a counterclockwise oriented closed line, parameterized over [0,2*pi[. The input variable t (the parameter) is a vector with all of its elements within [0,2*pi[. 

The function returns, depending on the flag der:

• der = 0: the coordinates of the points corresponding to the parameter t.
• der = 1: the coordinates of the tangent vectors (the first derivative of the parameterization).
• der = 2: the second derivative of the parameterization.

The last input variable, settings, is a row vector with five elements: 

• settings(1:2): the coordinates of the ellipse's center.
• settings(3:4): semi-major and semi-minor axis' lengths.

• settings(5)   : a flag (-1 or 1) for the orientation of the boundary:
  • 1 means counterclockwise orientation.
  • -1 means clockwise orientation.

We recall that if the ellipse is a link of an articulated body, it must be centered at the origin. if not, the boundary will be automatically shifted when compiling the DAT-File.

See also:

Fluid's boundaries

bht_boundary_check

2008 - A. Munnier and B. Pincon (Insitut Elie Cartan and INRIA Lorraine, Projet CORIDA, Nancy, France).