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. Fuwei. Our partners will collect data and use cookies for ad personalization and measurement. scooter wiring diagram electric wuxing xm. How to do Piezoelectric coupling in ANSYS-APDL or COMSOL between tapered substrate and rectangular piezoelectric patch? It's also possible to easily define dependent variables and identify coefficients via the General Form PDE interface. In the most general case, it can be an anisotropic tensor: Next, we need to know what all of these variables are called, internal to the COMSOLMultiphysics architecture. One such solution is a Lorenz attractor, which looks like a figure eight or butterfly when plotted in the phase space. J+u*JB=-* , J and B are both vectors. Chercher les emplois correspondant Now design your own logo using straight lines and write up the equations of the lines that make up your design ou embaucher sur le plus grand march de freelance au monde avec plus de 22 millions d'emplois. Posted 12 ago 2014, 11:04 CEST Yes, you can click "Equation View" to edit equation. The terms being contributed to the equation by the node are also highlighted with a dotted line displayed under the respective part of the equation (as seen in the above screenshot), except for the parent physics interface node (shown below). Only if the main current density is parallel to the discs you can still use the 2D (xy-plane) model (in which case you still could use one PDE for each disc, and couple them through the continuity-contact resistance in the region of the small disc). If xy is the plane parallel to the discs, then surely you'll have a z component in J, and you talked only of x and y components. What's the best way to measure growth rates in House sparrow chicks from day 2 to day 10? To show this functionality in action, lets take a look at three examples. [math] J_y - \mu J_x B = -\sigma \frac{\partial \phi}{\partial y} [/math] Simply by adding this feature and applying it to all relevant domains, the above multiphysics coupling will be included in the model. I find that I can't write this equation into COMSOL using PDE module. A detailed description. Here is more about the contact resistance. Jesus. 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. To manually implement this same multiphysics coupling, you will need to be aware of the full equation that you want to implement, as well as how variables are implemented within the COMSOLMultiphysics architecture. This model (well-known) is for calculating velocity and . Jesus. I understand there are a lot of software programs that can simulate DED by going through specific modeling, simulation, and commands. 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. You advice really helps me a lot! To address this challenge, users can implement two sets of equations to describe various aspects of the electrical signal propagation. Using both sets of equations enables the visualization of complicated real-world phenomena. To solve the KdV equation in COMSOL Multiphysics, users can add PDEs and ODEs into the software interface via mathematical expressions and coefficient matching. 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. For this and other reasons, we highly recommend taking advantage of the software's predefined multiphysics interfaces or predefined multiphysics couplings whenever possible. Mastercool Swamp Cooler Wiring Diagram - School Cool Electrical old-school-new-body--review.blogspot.com. These waves are now called solitons, which are seen as single humps that can travel over long distances without altering their shape or speed. In my case, have the control problem. The differences between the unperturbed and perturbed solutions over time (left) and the normal pattern for a Lorenz attractor (right). 9 Replies, Please login with a confirmed email address before reporting spam. All the variables and equation contributions defined by each node in a physics interface become visible and editable (such as to couple physics). 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. Thank you very much! The stationary (time-invariant) form of the partial differential equation for electric currents is: where is the current, is the electric field, is the electric conductivity, and is the electric potential. Copyright 2022 FAQS.TIPS. Tutti i diritti sono riservati. How can I see the equations COMSOL is defining? I'm a new comer for COMSOL! We can use the Find tool to search for these quantities and locate the respective variables and expressions that define them. You can also access the equations and variables used for the physics through using the Report Generator. Hi. A manual implementation of the Joule heating multiphysics coupling. listed if standards is not an option). Thank you very much Our partners will collect data and use cookies for ad personalization and measurement. To provide this flexibility, COMSOL Multiphysics uses a built-in interpreter that interprets equations, expressions, and other mathematical descriptions before producing a model. When using certain parameter values and initial conditions, a system of ODEs (a Lorenz system) has chaotic solutions. It is usually studied in three spatial dimensions and one time dimension, although two (spatial) dimensional . Thank you again! Comsol solves equations, but the bubble can not move as Hi, I am studying micro bubbles flow in lungs for mechanical ventilation. 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. You mean like this: [math]\vec J+\mu[(\vec J*\vec n_y)*B*\vec n_x-(\vec J*\vec n_x)*B*\vec n_y]=-\sigma*\nabla \phi[/math] 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. coth (x) csc. This is a straightforward process when using the Global ODEs and DAEs interface to define the Lorenz system. Yes,you got what I meant.The equation is just like that. Can Hi all, I am simulating moving mesh in COMSOL where I need to apply Naveir-slip boundary condition (found in literature). I don't find any effect of this type of parameters. Toggle Sub Navigation. Its also possible to easily define dependent variables and identify coefficients via the General Form PDE interface. If it's just [math] \phi [/math], the way of implementation is very simple (if it's [math] \vec B [/math] you can expand the cross product and you should use several equations, one for each component). As a result, one of the main modern applications of solitons is in optical fibers. You can see the equation for any physics node in your model by selecting the respective node and in the Settings window, expanding the Equation section. Things change. And your problem hardly is 2D (well, it can be 2D axial-symmetry). 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! Lastly, lets take a look at the Lorenz equations, which were developed to serve as a simple mathematical model for atmospheric convection. Cotangent (argument in radians) cot (x) coth. Which Study Type Should I Use for My Electrothermal Analysis? I am really sorry I always decribe the problem ambiguously! Dose, anyone have some mph files which can support my effect of double bond on the flexibility of polymers. Please, can anyone upload an mph file for such a geometry or can guide me?. 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. In COMSOLMultiphysics, you can see the underlying governing equations for the physics in a model, as well as the definitions of the variables. This tool enables you to document all the details of your entire model. I will consider seriouly and maybe I can simplified the model into case two as you told me ! Thank you for your kind help! Today, engineers use the KdV equation to understand light waves. Best regards. If you want to learn more about this example, see the KdV equation model in the Application Gallery. 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. [math] J_y = -\frac{\sigma \left(\frac{\partial \phi}{\partial y} + \mu B\frac{\partial \phi}{\partial x} \right)} {1 + \mu^2 B^2} [/math], Support; MathWorks Fuwei. The term miscibility refers to the single-phase state in thermodynamics. 1. I have made a solid-state battery model based on electrochemical PDEs in COMSOL. You can fix this by pressing 'F12' on your keyboard, Selecting 'Document Mode' and choosing 'standards' (or the latest version listed if standards is not an option). In friction stir welding high heat input results in grain growth for aluminium.Grain growth is also higher for slower cooling rate in aluminium since time for growth will be more as a general Why forces and torque applied on a rotating body like shaft rotating and moving forward through a dense medium (ex. Any specific ideas? I find that I can't write this equation into COMSOL using PDE module. In the context of electrical signals, this pattern could generate effects similar to those of arrhythmia, a condition that disturbs the normal pulse of a heart. v.v=p+2v. I want to measure change of capacitance due to relative displacement between two parallel plates in COMSOL. All rights reserved. Copyright 2022 FAQS.TIPS. 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: Solving the FitzHugh-Nagumo equations at times of 120 (left) and 500 (right) seconds. I find that I can't write this equation into COMSOL using PDE module. The information is displayed all at once without needing to switch between selecting different nodes. Hi try a search in COMSOL help for: Built-In Operators Mathematical Functions and move "left" "right" through the help pages with the < > icons--Good luck This consent may be withdrawn. These equations are used to study the dynamics of spiral waves in excitable media. Your internet explorer is in compatibility mode and may not be displaying the website correctly. In the settings, you can see the variable names, expressions, units, and descriptions, among other details. Thank you very very much for you kind help. I have attached a picture of this equation.Thank you very much. Please, tell us what the dependent variable is and we will be able to help you better. If a physical model is not listed in the wizard, we can use Comsol's weak form to enter PDE's (governing equations of a system) in their weak form. Hi. Again, keep in mind that any nonlinearities present in the materials will be automatically incorporated into this definition. 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. What are your Hi friends, Dels is a surface gradient operator which we applying to find the tangential velocity along a surface/arc. If we are only interested in searching within the report preview, we can select the respective tab for it in the Graphics window and use the keyboard shortcut Ctrl+F to search locally within the generated report preview text. 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 am trying to simulate the tensile test of PCL scaffolds. af'' (x) + b (x)f (x) = Ef (x), where E is an unknown constant that will be determined by the boundary conditions. for example: 2 equations of momentum (2D flow) coupled with continuity equation, This model (well-known) is for calculating velocity and pressure fields. The Show More Options dialog box accessed through the Model Builder toolbar. The very good agreement between our COMSOL model and the experimental results for the inductance gives a high level of confidence to our model. Some examples of models that demonstrate manual couplings include: If you are solving such models as a stationary (time-invariant) problem, see: Improving Convergence of Nonlinear Stationary Models. Cosecant (argument in radians) Hi,Mr Lucio 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. Yes. 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). I can help with COMSOL. Enable displaying the Equation View nodes for all the physics feature nodes in your model tree by selecting the respective check box. I want to write differential modified heat transfer equation in comsol.please help me in this regard, http://www.comsol.com/blogs/equation-based-modeling-in-comsol-4/. If you isolate the components of [math] \vec J [/math], you get: How to build fluid structure interaction simulation for elastic ring squeeze film damper in COMSOL? The ability to define arbitrary, and user-defined, couplings between existing physics interfaces is one of the core capabilities of COMSOLMultiphysics. Proficiency with CFD software such as Ansys Fluent, Comsol, or any other simulation package. I shall be very thankful. But due to less information about bubble simulation, I cannot. Use this solution u 0 as initial guess in the iterative problem, a weak form of poisson problem, u k + 1 v d x = u k v d x + F ( u k), for k = 0, 1,., and where F involves some stuff nonlinear in u k. In addition, I need my F ( u k) to include both averages and jumps across elements (it's some penalty method). So, how I develop my new PDE or physical problem. The rhythmic contractions are triggered when the heart passes an ionic current through the muscle. The results show the diffusing species and the characteristic spiral patterns, which increase in complexity over time. But another problem arises that how to define the x ,y component of J (the current distributed on the plane) Introduction to Defining Multiphysics Models. The incompressible Navier-Stokes equations is also available as a built-in pre-defined Navier-Stokes physics mode in the FEATool FEM Matlab toolbox. However, regardless of the strain, I have the elastic region all the time which is not true when it Is it possible to implement FBM in a commercial FEA software package, such as FEMLAB, COMSOL, or open source software like Moose? listed if standards is not an option). Thank very very much!!! So it's the first option I told you about. Think on which variable must have continuity (in the contact line) and which one must not: I suppose both [math]J_x[/math] and [math]J_y[/math] must be continuous and [math]\phi[/math] can have a discontinuity. If a physical model is not listed in the wizard, we can use Comsol's weak form to enter PDE's (governing equations of a system) in their weak form. In this case the equations are in 2D defined as rho_ns*u' - miu_ns* (2*ux_x + uy_y + vx_y) + rho_ns* (u*ux_t + v*uy_t) + p_x = Fx_ns Or, if solving in the time domain, see: Controlling the Time Dependent solver timesteps. So if in your equation you had some derivative in [math]J[/math], you could use a pair of PDE's. OK, Demonstrated ability to write concise and accurate technical documents and give strong technical presentations to a wide variety of audience. Thanks in advance, How to write the average Nusselt formulation: -8*Al*Al*integral of(-dT/dz(r,0)*r*dr)from(0 to 1/2/Al). Your internet explorer is in compatibility mode and may not be displaying the website correctly. [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). The other one is where the contact resistance lies. Oualid Imene. Anup Paul Send Private Message Flag post as spam Dear friend Can anyone help me to write the following equation in comsol dX/dt= (A)* [exp {-E/RT}] where A, E & R=constant T=variable want to solve to find out X.. rgds Anup 7 Replies Last Post 8 nov. 2013, 14:11 UTC+1 Pietro Pollaci Send Private Message Flag post as spam Jesus. My Email: athenaserra@gmail.com. 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. (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) Dear friends, I am interested in the solution of the following ODE with maximum accuracy using Euler method. I attach two picture of the device, one of the cross-section and top-down views of the device. Equation View You can access the equations and variables used internally by COMSOL Multiphysics by enabling the Equation View nodes to display in the model tree. 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. Xm 3000 Electric Scooter Wiring Diagram hestiahelper.blogspot.com. One such example is the Electrical Signals in a Heart model, provided through the courtesy of Dr. Christian Cherubini and Prof. Simonetta Filippi from the Campus Bio-Medico University of Rome in Italy. In short, to solve for Joule heating, one must solve for both the electric currents as well as the heat transfer governing equations. 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. Thanks. Learn how we and our ad partner Google, collect and use data. Learn how we and our ad partner Google, collect and use data. Set a boundary condition (BC) of continuity in one side (for instance at domain 1, Dirichlet BC: J1x = J2x and J1y = J2y). My focus is to solve nonNewtonian problem with addition of temperature effect or energy. COMSOL does not return it automatically, which makes our approach useful for those seeking a simple and effective model to study magnetostatic problems in a superconductor. Set a non-continuity BC at the other side, related to the contact resistance (at domain 2:
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