Use a Particle Tracing with Mass plot in 2D (
) or 3D (
) to visualize the trajectory of a particle with mass and subject to a flow field. Add a
Color Expression,
Deformation,
Translation,
Transparency (3D only), or
Visual Effects (3D only) as needed. Right-click a
2D Plot Group or
3D Plot Group to add these plot types from the
More Points Plots submenu.
for the pathline x ( t ). Here,
m is the particle’s mass,
F equals the force acting on the particle, and
t is time. This is a system of ODEs for
x, which COMSOL Multiphysics solves using a pair of Runge-Kutta methods of orders four and five. The solver advances the algorithm with the solution of order five and uses the difference between the order-five and order-four solutions to obtain the local error estimate.
where m is the particle mass and (
r,
φ,
z) are the cylindrical coordinates. The variable corresponding to the velocity component in the
φ direction (the default name is
partv) has the dimension length/time, and equals
as
has the dimension radians/time.
Specify the total force acting on the particles. Click the Replace Expression (
) or
Insert Expression (
) button to select predefined expressions based on the physics of the model. Or enter an
Expression — for 2D, enter or select
Fx and
Fy components of the force; for 3D, enter or select
Fx,
Fy, and
Fz components of the force. Enter a
Description (or edit the default). When some predefined forces are added, there are additional
Parameters with a
Value to enter into a table.
Enter the particle Mass. Enter the
Initial velocity — for 2D enter values for the
x-component and
y-component; for 3D enter values for
x-component,
y-component, and
z-component.
Under Advanced, define the
Particle velocity variables. Edit the default variable component names for each particle’s velocity. The default names are
partu (
x component),
partv (
y component), and
partw (
z component).
Under Advanced, also define these settings as needed and described for
Particle Tracing. Go to
Advanced — Termination and
Advanced — Instantaneous Flow Field for details.