To set the boundary conditions, right click on transport and choose concentration. You can specify boundary conditions through constraint, thereby you can set as many as you need. Two coupled oscillators with periodic parametric excitation. Walter frei explains what these boundary conditions mean and when they should be used. Now the question is how i should define the kvector to be used with a periodic floquet boundary condition in comsol. World leader in multiphysics simulations hq in stockholm. In solid state physics, bloch generalized floquets results to 3d systems and obtained the description of the wave function associated with an electron traveling across a periodic crystal lattice. Dec 03, 2015 imposing such constraints, comsol multiphysics looks for a solution that satisfies the acoustical dynamics and the boundary condition. Yields knowledge of whether all solutions are stable. Jun 06, 2017 the model includes floquet periodic boundary conditions on the left and right sides of the modeling domain and a port boundary condition at the top and bottom. This discussion is about an older version of the comsol multiphysics software. Imposing such constraints, comsol multiphysics looks for a solution that satisfies the acoustical dynamics and the boundary condition.
Using periodic boundary conditions use periodic boundary conditions, periodic edge conditions, and periodic point conditions to define a constraint that makes two quantities equal on two different but usually equally shaped domains. If not, use the traditional noslip velocity wall boundary condition and resolve the flow in the edl. Floquet theory applicable to linear ordinary di erential equations with periodic coe cients and periodic boundary conditions. This periodicity can be continuous the default or antiperiodic and can control which of the dependent variables that the periodic. Convected wave equation and absorbing layers benchmark tutorial, shows absorbing layers in action. Comsol defines a general mixed boundary condition as comsol ab, 2005a. Equation for floquet periodicity is h dst h srcexpj k r dst r src, where indices dst and src represent destination and source boundaries. How to model the optical properties of rough surfaces comsol. Impedance models are really models of a full flow, that is, a condition imposed simultaneously on the acoustic pressure and acoustic velocity, defining a given relation between the two elements.
The combination of comsol products required to model your application depends on several factors and may include boundary conditions, material properties, physics interfaces, and part libraries. The boundary element method bem is included in the acoustics module as a physics interface. Rightclick on nonisothermal flow, then go to the turbulent flow tab and add a boundary condition inlet. This boundary condition is controlled by maximum height of ponding in the same manner as described for the specified flux boundary condition see above. To assign the flow boundaries of the model, we will add inlet and outlet conditions for the water and air flows. It also provides a quick introduction to creating applications using the application builder. It also shows h ow these results are related to the geom etry and the boundary condition of the m odel. Problem with a boundary condition in comsol physics forums. The old main page crushed, thus this is the temoral solution. Comsol multiphysics simulations of the electric field and gas flow in a microwave axial injection torch a.
A t x, \displaystyle \dot xa tx, a t \displaystyle \displaystyle a t a piecewise continuous periodic function with period. Remember that concentration varies exponentially with potential in the double layers. Use for applying periodic boundary conditions with high accuracy requirements, such as cyclic symmetry in structural mechanics applications floquet boundary condition for electromagnetic wave propagation available for domains, faces and edges automatic orientation of source mesh on destination. Perfect electric conductor pec boundary condition, lossless, nonpenetrable geometrically very thin, conductive, and lossy transition boundary condition, lossy, skindepth dependent penetration, modeled in 2d conductive, electrically much thicker than skindepth. The port boundary condition at the top launches a plane wave at a specified angle of incidence and computes the reflected light, while the one at the bottom calculates the transmitted light. An introduction to shape optimization tutorial model. This constrains the temperature to be equal to the given value, unless the given value happens to be the. In section 5 coupled wave theory for periodically layered media based on a perturbation analysis is described, while in section 6 the realization of a.
The animation below, created using the gaussian pulse in 2d uniform flow. This is a reduced version of the presentation without figures for the coil case. Note that at a given boundary, different types of boundary. Modeling electroosmotic flow and the electrical double layer. The periodic boundary condition and pml question about comol 4. Lecture 6 boundary conditions applied computational fluid. Plasmonic wire grating wave optics comsol multiphysics. To model the layer within comsol im using the transition boundary condition. It is clear that this work only for plane waves, and that source and destination boundaries need to. From the boundary selections list, choose inlet water.
Sep 11, 20 to assign the flow boundaries of the model, we will add inlet and outlet conditions for the water and air flows. Walter frei explains what these boundary conditions mean and. Comsol multiphysics simulations of the electric field and. As a result, snells law of illumination light at the boundary of vacuum and silicon is reappeared in fig. Experiences from modeling very thin structures in comsol multiphysics bergen comsol user group workshop april 10th 20. In section 3 and 4 some general properties of periodic structures floquetbloch theorem and the bragg condition are deduced. In my study i am doing a simulation of a 2d flow, with the boundary conditions. Floquets seminal paper dealt with the solution of 1d partial differential equations with periodic coefficients. Boundary conditions can be used to simplify geometry or make meshing more efficient material properties for surfaces finite conductivity imperfect conductor perfect electric or magnetic conductor surface approximations for components lumped rlc layered impedance radiation absorbing boundary condition perfectly matched layers pml febi boundary. Electric field of a charged sphere texas state university. Zaj ckov a faculty of scienceceitec, masaryk university, kotl a rsk a 2, 611 37 brno, czech republic abstract the electric eld and the gas ow in the reactor chamber of a microwave axial injection torch were simulated. Feb 21, 2009 hi, im a chemical engineering student with a little problem with comsol multiphysics. Electric field of a charged sphere, brice williams, wim geerts, summer 20, 4 so summarizing, the above shows that the spatial distribution of the electric field given by a solution of poissons or laplaces equations correspond to a state of minimum field energy integrated over the systems volume. Comsol multiphysics is a simulation platform that encompasses all of the steps in the modeling workflow from defining geometries, material properties, and the physics that describe specific phenomena to solving and postprocessing models for producing accurate and trustworthy results.
Uber comsol multiphysics modellierungsbeispiele zum. Only the cases of frictionless problem are considered. To implement a periodic boundary condition in femlab, go through the following steps. Comsol and analytical results by plotting them on the same graph. Introduction to nanoparticle characterization in comsol. The thermal conductivity of water can be approximated at 0. Experiences from modeling very thin structures in comsol.
Lecture series on chaos, fractals and dynamical systems by prof. How to make boundary conditions conditional in your simulation. The port and lumped port boundary conditions can help simplify the modeling of wave electromagnetics problems. Banerjee,department of electrical engineering, iit kharagpur. The first term is the prescribed temperature, which you enter as input. This model was developed through reference to the modeling techniques deve loped in the continuous casting model in sthe heat.
The use of comsol for integrated hydrological modeling. The immediately following section provides a brief introduction to comsol and the chemical engineering module, which together form the basis for the models just listed. Particular functionality may be common to several products. New impedance boundary conditions for acoustics simulations. Use of the perfect electric conductor boundary conditions to. Comsol multiphysics software understand, predict, and optimize. Mar 19, 2018 the boundary element method bem is included in the acoustics module as a physics interface. Use for applying periodic boundary conditions with high accuracy requirements, such as cyclic symmetry in structural mechanics applications floquet boundary condition for electromagnetic wave propagation available for domains, faces and edges automatic orientation of source mesh on. The specified value is the total volumetric flow rate in units of l 3 t into the domain across a surface swept out by revolving the boundary segment 360 degrees about the z axis. Many nearly most with in engineering odes have smooth, continuous phase spaces the hypothetical space inhabited by solutions where numerical solvers dont have to make very tiny increments to their independent variable step size to come up with. How to make boundary conditions conditional in your. Mar 09, 2015 the port and lumped port boundary conditions can help simplify the modeling of wave electromagnetics problems.
How to model a shell and tube heat exchanger comsol blog. On the other hand, your problem seems to fit acdc module in comsol. Now look at the temperature boundary layer by specifying a temperature of the plate as 40c and the water temperature of 20c. Complex refractive index of material is determined by reference to a comprehensive book by e. Select the no flux button and notice that the boundary 1 not applicable, since the program satisfies it without intervention by us due to the. Floquet theory is widely used in the analysis of stability of dynamical systems, including the mathieu equation and hills differential equation for approximating the motion of the moon. Implementation of periodic boundary condition comsol.
The floquet bloch theory is presented as an alternative to them. The available the available study types are listed in table 11 with column definitions after the table. It provides an overview of the comsol environment with examples that show you how to use the comsol desktop user interface and the model builder. Because according to flux bc in comsol, having the convection term or not on the left hand side seems to have impact on the defined boundary condition right hand side. In am simulating plane waves incident upon a stack of thin films at oblique angle of incidence, each layer with different real part of refractive index, e. Use of the perfect electric conductor boundary conditions to discretize a diffractor in fdtdpml environment c. At the layers outer boundary, a simple planewave impedance condition removes all of the remaining waves, since normal incidence has been ensured. In section 3 and 4 some general properties of periodic structures floquet bloch theorem and the bragg condition are deduced. The model includes floquet periodic boundary conditions on the left and right sides of the modeling domain and a port boundary condition at the top and bottom. How comsol implementinterpret flux boundary condition in the.
The second term is just the temperature degree of freedom cast into a variable. Jul 27, 2010 stiff boundary condition is a term borrowed from numerical solutions to differential equations. Idea if a linear di erential equation has periodic coe cients and periodic boundary conditions, then the solutions will generally be a. It is a class of periodic boundary conditions called floquet conditions, and they are very simple. The periodic condition node adds a periodic boundary condition. Ansys high frequency structure simulator hfss tutorial. When using a neumann boundary condition, one prescribes the gradient normal to the boundary of a variable at the boundary, e.
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