How do I apply periodic boundary conditions in Comsol?

To add a periodic boundary condition, in the Model Builder, right-click a physics interface node and select Periodic Condition. The periodic boundary condition typically implements standard periodicity so that u(x0) = u(x1) (that is, the value of the solution is the same on the periodic boundaries).

How do you impose periodic boundary conditions?

To apply the periodic boundary condition, the classical method consists in enforcing the same value for degrees of freedom of matching nodes on two opposite RVE sides. Thus, it requires a periodic mesh, which has the same mesh distribution on two opposite parts of the RVE boundary.

How are periodic boundary conditions defined?

Periodic boundary condition (PBCs) are a set of boundary conditions which are often chosen for approximating a large (infinite) system by using a small part called a unit cell. PBCs are often used in computer simulations and mathematical models.

What is Floquet periodicity on Comsol?

The most common method of determining the dispersion curves of a periodic waveguide is to use, what COMSOL Multiphysics software refers to as, Floquet boundary conditions (Floquet BC). These boundary conditions, and methods involving them, are called different things depending on the field of study and application.

What is Floquet periodicity?

The Floquet periodicity can be used for frequency domain problems with a spatial periodicity of the geometry and solution. The Cyclic symmetry is a special case of a Floquet condition, intended for structures which consist of a number of sectors which are identical when rotated around a common axis, like in a fan.

Why do we apply periodic boundary conditions?

Periodic boundary conditions are often used to simulate a portion of a larger tissue, such that agents exit and enter the simulation space with similar frequencies and there is no flux of agents out of the tissue.

What is periodic boundary conditions CFD?

Periodic boundary conditions are used when the physical geometry of interest and the expected flow pattern have a periodically repeating nature. This means that the flows across two opposite planes in your computational model are identical.

What is periodic boundary condition in fluent?

Periodic boundary conditions are used when the physical geometry of interest and the expected pattern of the flow/thermal solution have a periodically repeating nature. (In FLUENT 4 this is a “periodic” boundary.)

What are Floquet modes?

Fundamentally, Floquet modes are plane waves with propagation direction set by the frequency, phasing, and geometry of the periodic structure. Just like Wave modes, Floquet modes too have propagation constants and experi- ence cut-off at low frequency.

What is a Floquet system?

Floquet theory is a branch of the theory of ordinary differential equations relating to the class of solutions to periodic linear differential equations of the form. with a piecewise continuous periodic function with period. and defines the state of the stability of solutions.

What is Floquet stability analysis?

Floquet stability analysis is similar to linear stability analysis of steady base flows. Each eigenvalue of this operator shows the growth/decay rate of the perturbation over a period: these are the Floquet multipliers ( ). When , the flow is unstable and the perturbation grows each period. …