Thank you very much! I have been trying to simulate heat transfer problem in Comsol 5.5 for long time but it always throw an error stating: "Failed to find a solution. During this process, ions flow through small pores that exist in an excitation (open) or rest (closed) state within the cellular membrane. Moving on to a medical example, lets see how simulation can be used to understand the rhythmic patterns of contractions and dilations in a heart. You can generate a report that displays within the software and includes this information by completing the following steps: The report Preview tab in the Graphics window provides you with a convenient, at-a-glance view of all the equations and variables for the physics nodes. Please, can anyone upload an mph file for such a geometry or can guide me?. The screenshot below shows the variable name, expression, unit, and description for the components of the electric conductivity tensor, as well as the isotropic value. .v=0. Yes. Actually,the contance resistance is the situation one as you understand! The ability to define arbitrary, and user-defined, couplings between existing physics interfaces is one of the core capabilities of COMSOLMultiphysics. Here is the link to my model: https://www.researchgate.net/publication/334724548_model2mph?_sg=7xnb1zSpi-CINUAzRvo9VdZOMFw2LyRFF1ktU5yvmAtDLpKkaCfw0Nl2Yz64ZTgmezryctFLRcN1fwltzszT3gm9vx3WzwbUBae8iH6n.5e0t9FTZ4WEVDBfFVIMOtaFm4Fek_p4nV7DJH-_J0Kx-psc68rt2whxg2VqhVSVfbwUeAvzY0jNABl3Ek13hgQ. Can Hi all, I am simulating moving mesh in COMSOL where I need to apply Naveir-slip boundary condition (found in literature). Thank you. Dear friends, In the attached MPH file, I am simulating a gas bubble moving in fluid using COMSOL moving mesh application. Please, tell us what the dependent variable is and we will be able to help you better. Thank you for your kind help! With equation-based modeling, part of the core functionality of COMSOL Multiphysics, you can create your own model definitions based on mathematical equations and directly input them into the softwares graphical user interface (GUI). How to write variables in Phase Field Method, Guidelines for Equation-Based Modeling in Axisymmetric Components, How can I check if I can connect to the license server, How to Implement the Weak Form for Time-Dependent Equations, Galleria dei Modelli e delle App di Simulazione, 2022 da COMSOL. If you want to learn more about this example, see the KdV equation model in the Application Gallery. Simulation showing how solitons maintain an intact shape when colliding and reappearing. For this and other reasons, we highly recommend taking advantage of the software's predefined multiphysics interfaces or predefined multiphysics couplings whenever possible. I have been wondering whether there is a simple symbol to define cross product. L'inscription et faire des offres sont gratuits. Defining Multiphysics Models Automatically with Multiphysics Interfaces, Defining Multiphysics Models Manually with Predefined Couplings, Defining Multiphysics Models Manually with User-Defined Couplings, Viewing and Accessing the Equations and Variables for Physics Feature Nodes, Coupling Physics Between Model Components for Multiphysics Models. Later these may be used for statistical analysis like pca. Next, users can view an initial solution close to the attractor and study the growth of a very small perturbation to this initial data. How to do Piezoelectric coupling in ANSYS-APDL or COMSOL between tapered substrate and rectangular piezoelectric patch? Cosecant (argument in radians) Solving the complex Ginzburg-Landau equations at times of 45 (left) and 75 (right) seconds. Thank you very very much for you kind help. To solve the Lorenz attractor model, the Lorenz equations a system of three coupled ODEs that contain three degrees of freedom need to be added into the software. Another problem:In my 2D PDE model,there are two circle disk adhere to each other(I attached a picture of the model).And small and big disk are made of different materials. A detailed description. J+u*JB=-* , J and B are both vectors. OK, About the other question (contact resistance), I don't have clear if you refer to the contact between both discs, in the z direction (in which case your problem would have 2 fields of dependent variables, one for each disc) or you refer to the contact between the central disc and the surrounding circular band: in this case you can model the contact resistance in this way: I understand there are a lot of software programs that can simulate DED by going through specific modeling, simulation, and commands. Which Study Type Should I Use for My Electrothermal Analysis? In addition, the simulation reveals that, just like with linear waves, solitons can collide and reappear while maintaining their shape. [math] \phi_2 = \phi_1 + (\vec J_2 \cdot \vec n_2) R[/math], or a similar relation, where [math]R[/math] is some scalar resistance in the contact line and [math]\vec n_2[/math] is the unit vector normal to the contact line and pointing outwards from domain 2). First, we expand the full equation that we want to implement, the source term in the Heat Transfer governing equation: where here is an isotropic (scalar) value. Regardless of the multiphysics couplings that you will want to implement manually, the approach will be similar to what has been briefly described above and discussed in detail separately. The Joule heating effect introduces a heat load of the form: The above coupling is automatically included via the Electromagnetic Heating multiphysics coupling feature, as shown in the screenshot below. But another problem arises that how to define the x ,y component of J (the current distributed on the plane) Since, the growth curve from day 2 to 10 won't be like the "Logistic curve" it might not follow logistic Hi, I am after the reference below, my library says it cannot obtain a copy either locally or internationally, any help appreciated! Note that while COMSOL employees may participate in the discussion forum, COMSOL software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team. I simplified the 3D model into 2D model,which has bee proven to be right in several published papers.The two discs adhere to each other and the contact resistance lies on the contact surface. Hi , any idea on how I can get the properties for Potassium Sodium Niobate for simulation in COMSOL? The results show the diffusing species and the characteristic spiral patterns, which increase in complexity over time. Cotangent (argument in radians) cot (x) coth. As a result, one of the main modern applications of solitons is in optical fibers. These equations are used to study the dynamics of spiral waves in excitable media. Thank you very much And in my 2D model, the magnetic field is normal to the plane,You tell me that maybe I can just expand the cross product. The rhythmic contractions are triggered when the heart passes an ionic current through the muscle. How to build fluid structure interaction simulation for elastic ring squeeze film damper in COMSOL? Using the command mphplot(model,'pg1', 'LineWidth', 2) dose not work. It is usually studied in three spatial dimensions and one time dimension, although two (spatial) dimensional . So the contact area is equal to the surface of the central disk. J+u*JB=-* , J and B are both vectors. One of the more common examples of a multiphysics coupling is Joule heating, where the flow of electrical current through a conductive material leads to heat losses, which lead to a rise in temperature. The overall approach is the same if implementing couplings on domains or as boundary conditions. If you are not using the existing physics interfaces in the software, you will need to manually create and define yourself all of the intermediate variables and nonlinear material relationships via variables and functions features underneath the Definitions node. With this setup, users are able to model an initial pulse in an optical fiber and the resulting waves or solitons. Lastly, lets take a look at the Lorenz equations, which were developed to serve as a simple mathematical model for atmospheric convection. Once enabled, there will be an Equation View node underneath each physics node that contains a list of all internally defined variables for the respective node. af'' (x) + b (x)f (x) = Ef (x), where E is an unknown constant that will be determined by the boundary conditions. mastercool evaporative symphony schematron evap. You advice really helps me a lot! You say:"But as appears with no derivative, I think it's easier to isolate each component and define them simply as expressions." In addition, the simulation demonstrates that with the chosen parameter values, the Lorenz system behaves like a Lorenz attractor, with results showing the butterfly shape that these attractors are known for. It is also important to note that this feature will automatically account for any nonlinear material properties, such as, for example, thermal and electrical conductivities that are temperature dependent. cosh (x) cot. During this transition, the amplitude of oscillations gradually increases and the periodicity decreases. What are your Hi friends, Dels is a surface gradient operator which we applying to find the tangential velocity along a surface/arc. Hi. Again, keep in mind that any nonlinearities present in the materials will be automatically incorporated into this definition. The information is displayed all at once without needing to switch between selecting different nodes. Answers. Best regards. The other one is where the contact resistance lies. multiphysics couplings already built into the software, using functions to define material properties, Improving Convergence of Nonlinear Stationary Models, Controlling the Time Dependent solver timesteps, thermal_actuator_jh_user-defined.mph (1 MB), See how the variables are calculated by the software, See the names of variables and the quantities each one defines, Access and use the variables when formulating expressions, Edit any variables and equation contributions defined and used internally by the software, More easily search and find variables defined by each physics interface and physics feature node, Define custom multiphysics couplings between physics interfaces, A preview of the report will appear in a new tab in the, Navigate to the physics interface or physics feature node which you want to see the equations and variables for. To solve the KdV equation in COMSOL Multiphysics, users can add PDEs and ODEs into the software interface via mathematical expressions and coefficient matching. How can I see the equations COMSOL is defining? scooter wiring diagram electric wuxing xm. To show this functionality in action, lets take a look at three examples. The results (seen in the left image below) visualize how the difference between the original and perturbed problems increases over time. Studying the electrical signals in a heart is not a simple process and involves modeling excitable media. I am new COMSOL, but I understand few things. Any specific ideas? How to Create High-Quality Model Images in COMSOL Multiphysics, How to Use the Platonic Solids as Geometry Parts in COMSOL. So if I understand well, [math] \vec J [/math] only has x and y components, and [math] \vec B [/math] only has z component (say [math] B [/math]), then you get these 2 equations: 4. I do not know its role in moving mesh free surface (air-liquid) flow. Hi, I am using Comsol to simulate a bubble moving in blood vessel. In my simulation i am applying moving mesh (ale) application mode. I can't understand what you meant by "in which case your problem would have 2 fields of dependent variables, one for each disc".Can I solve the problem just as you describe above? Piezoelectric coupling between the rectangular substrate and rectangular Hi, I am trying to construct a multi-layer fibril structure from a single layer in PyMol by translating the layer along the fibril axis. By providing your email address, you consent to receive emails from COMSOL AB and its affiliates about the COMSOL Blog, and agree that COMSOL may process your information according to its Privacy Policy. Here I am facing this problem. (When expanding the cross product ,[math] \vec J*\vec n_y[/math] is the y component of [math]\vec J [/math] and I think B is simply a number,not a vector) The differences between the unperturbed and perturbed solutions over time (left) and the normal pattern for a Lorenz attractor (right). Thanks. This consent may be withdrawn. According to the KdV equation, the speed of the pulse should determine both its amplitude and width, which can be observed via simulation. How can it be done ? We will also demonstrate how to perform all of the items listed above using an example toward the end of this article. To learn how to define material properties that are dependent upon variables being solved for, you can watch a tutorial video on using functions to define material properties. I find that I can't write this equation into COMSOL using PDE module. My Email: athenaserra@gmail.com. The COMSOL weak form pdes application mode was applied but Hi friends, If we publish all papers in MDPI SCI journals during PhD studies, is it good?. Note that once you add this coupling manually, you should remove the built-in coupling from the Multiphysics branch, which was shown earlier. We can use the Find tool to search for these quantities and locate the respective variables and expressions that define them. Whatever your equations, write your equations in a matrix form on a paper see attached file-1, then go to model wizard choose your domain (1D, 2D or 3D) then choose mathematics, then choose. I would appreciate the help. listed if standards is not an option). Since the equation doesnt introduce dissipation, the waves travel seemingly forever. Tutti i diritti sono riservati. If I want to define the contanct resistance on the contact area,which boundary condition should I use in the PDE module? In short, to solve for Joule heating, one must solve for both the electric currents as well as the heat transfer governing equations. Proficiency with CFD software such as Ansys Fluent, Comsol, or any other simulation package. Hi But due to less information about bubble simulation, I cannot. I have conducted and published a systematic review and meta-analysis research with the topic related to public health and health pomotion (protocol was registed in PROSPERO). Hyperbolic cotangent. I am trying to simulate the tensile test of PCL scaffolds. To address this challenge, users can implement two sets of equations to describe various aspects of the electrical signal propagation. If [math]\phi[/math] is really not a dependent variable, you must know it in advance (for instance, as a function of x and y), and you can include its spatial derivatives just as phix or phiy. Example of the typical shape of a Lorenz attractor. I do not mean the compatibility of different components. In the settings, you can see the variable names, expressions, units, and descriptions, among other details. I am not used to using COMSOL so I don't know if it is possible to solve this problem. Finally you say: "But another problem arises that how to define the x ,y component of J": if they are dependent variables, you don't know them a priori, you want to solve them: you only need boundary conditions for them. Hi,Jesus, Your internet explorer is in compatibility mode and may not be displaying the website correctly. It can be written as Dear friends, I a have a problem in setting the line width of a graph in COMSOL/MATLAB live link simulations. Further discussion of this topic, along with a comprehensive introduction, is provided in an article Defining Multiphysics Models Manually with User-Defined Couplings. It's also possible to easily define dependent variables and identify coefficients via the General Form PDE interface. I have made a solid-state battery model based on electrochemical PDEs in COMSOL. Watch a quick video introduction to COMSOL Multiphysics to learn more about the softwares key features. 3. Yes,you got what I meant.The equation is just like that. Adding a Global equation to a PDE in COMSOL Multiphysics, Accumulation of Heat example. However, if we assume isotropic electric conductivity, one convenient way to write it is: The expression can now be added as a domain Heat Source term within the Heat Transfer in Solids interface, as shown in the screenshot below.
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