Particle Properties
Use the Particle Properties node to set properties based on the Formulation selected from the physics interface Particle Release and Propagation section. Set the particle velocity for Massless formulations, or particle mass for Newtonian, Newtonian, first order, Lagrangian, or Hamiltonian formulations.
For theory see:
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Newtonian Formulation
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Hamiltonian Formulation
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Lagrangian Formulation
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Massless Formulation
Particle Mass
This section is shown when Newtonian, Newtonian, first order, Hamiltonian, or Lagrangian is selected as the Formulation.
Enter a value or expression for the Particle mass mp (SI unit: kg). The default expression is me_const, which is a predefined physical constant for the electron mass, 9.10938356 × 10−31 kg.
If the Relativistic correction check box is selected in the physics interface Advanced Settings section, instead enter a value or expression for the Particle rest mass mr (SI unit: kg). The default expression is me_const.
Lagrangian
This section is shown for The Mathematical Particle Tracing Interface and when Lagrangian is selected as the Formulation.
Enter a value or expression for Lagrangian L (SI unit: J). The default is 0. The Lagrangian is usually a function of the particle kinetic energy and fields, which exert a force on the particles. To include field forces in the Lagrangian, it should be possible to express the field in terms of the gradient of a potential.
For example, the expression pt.mp*(pt.vx^2+pt.vy^2+pt.vz^2)/2 is the Lagrangian for a free particle in 3D, not subjected to any forces.
Particle Velocity
This section is shown when Massless is selected as the Formulation.
Enter a vector for the Particle velocity v (SI unit: m/s) based on space dimension. For Massless, the particles follow streamlines of the particle velocity expression.
Hamiltonian
This section is shown for The Mathematical Particle Tracing Interface and when Hamiltonian is selected as the Formulation.
Select an option from the Specify Hamiltonian list: Directly (the default) or Manually.
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For Directly enter a value for Hamiltonian H (SI unit: J) The default is 0. The Hamiltonian is typically a function of the particle kinetic energy and any fields which would induce a force on the particles. For example, in 3D the Hamiltonian of a free particle is (px^2+py^2+pz^2)/(2*pt.mp).
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For Manually enter coordinates for the Particle velocity vH (SI unit: m/s) and Hamiltonian Force FH (SI unit: N) based on space dimension.
The Hamiltonian formulation solves a system of first order ordinary differential equations for the particle coordinate and the particle momentum. Thus, when using the Hamiltonian formulation, the number of degrees of freedom is the same as the Newtonian, first order formulation and twice as high as the Massless, Lagrangian, and Newtonian formulations.
The Particle Properties node is a default feature for all particle tracing physics interfaces. It is possible to add more than one instance of this Particle Properties node to the same model. When you do so, each instance corresponds to a different species of particle. For example, two Particle Properties nodes could represent ions and electrons, or white blood cells and bacteria.
When two or more species are in the same model, you can decide which species is released by each particle release feature, such as the Release, Inlet, or Release from Grid feature. To do so, select the appropriate Particle Properties node from the Released particle properties list in the physics feature Released Particle Properties section.
For more information, see Particle Tracing with Multiple Species in the Particle Tracing Modeling chapter.