You represent and warrant that you are not subject to any comprehensive sanction or embargo by the U.S. or any other country, nor are you identified on any list maintained by the U.S. government that identifies persons for which the U.S. maintains restrictions. Please login with a confirmed email address before reporting spam . Your Discussion has gone 30 days without a reply. Posted 21.12.2009, . Good luck rgds Thank you. 0 Replies, Please login with a confirmed email address before reporting spam, Dear all I need to impose a user defined boundary condition at the surface of the solid which is in contact with the coolant. However, in my problem the solid is under laser heating (consider as a volumetric heat generation based on Beer-Lambert law)in which i am defining optical properties for solid as well as for fluid such that fluid light absorption characteristic is greater than that of solid. Boundary conditions in heat transfer. A heat flux boundary condition was executed at the inner cylinder of the annular. Use the Preview button often. Hi, I am trying to model the time dependent thermal diffusion in a solid with the Heat Transer in Solids physics. Im a beginner with COMSOL and I don't understand how it calculates the normal heat flux on a boundary. The heat source is only active initially, and I would expect the model to reach thermal equilibrium with the surroundings/boundary conditions. The heat source is only active initially, and I would expect the model to reach thermal equilibrium with the surroundings/boundary conditions. Hello, I am using COMSOL 5.3a and solving a 3D model using the conjugate heat transfer, laminar flow study. Veryst Engineering The goal of COMSOL Access is to provide a forum for you to communicate effectively with COMSOL as well as your colleagues within the multiphysics simulation community. Never invent acronyms and use as few acronyms as possible. Matthew, Hence the Q variable (or q0_htgh internally) enters directly thermal power onto the boundary, while the "h" is proportional to the temperature difference (in K) of (Tinf-T) and T is the temperature you are solving for, so Tinf yould be your constant blood temperature, then h should be scaled to take into account the liquid solid exchange, but perhaps next step to take into account the blood flow, or total volume passing through, as the blood temperature might not manage to take/give all the heat, unaffected, if you have a sever feber, but I would propose not to use non-linear terms to start with. For example, write "COMSOL Multiphysics" and not "CMP". . You agree that you will not otherwise use your COMSOL Access account to violate or to assist anyone in violating any law. according to comsol help files: "Tinf is the external bulk temperature" and this is from the section of . The heat flux through internal boundaries can be automatically computed. Please check to see if a topic has already been posted. Whilst the heat source is active the model heats, then it holds at the max temperature instead of dissipating the heat. Avoid run-on sentences. Two physics (bioheat physics and moving mesh physics) are included in model to simulate a laser ablation over a part of the bone. These rules are subject to change. Posted May 11, 2022, 8:53 p.m. EDT 0 Replies . Further, you represent and warrant that you are not subject to any restriction on the receipt of technology or products under the export control laws of the U.S. or any other country. Posted Oct 2, 2012, 7:25 a.m. EDT If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help. The pipe was settled vertically . Try to catch typos. Posted Jul 29, 2020, 12:37 a.m. GMT+2 If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base. . Heat Transfer I am using a fixed constraint boundary condition on the surface where the part . That boundary condition accounts directly for heat loss from the solid through conduction and the fluid flow that results accounts for convection. Please login with a confirmed email address before reporting spam . -- Hence the Q variable or q0_htgh internally enters directly thermal power onto the boundary, while the "h" is proportional to the temperature difference in K of Tinf-T and T is the temperature you are solving for, so Tinf yould be your constant blood temperature, then h should be . The condition can be set on a boundary shared by the two interfaces or on two boundaries facing each other. In order to evaluate how to derive values in the Results section, I have followed the Heat sink tutorial included in COMSOL 4.2a and once I get the results of the simulation, I calculate the Surface Integration of the Total normal heat flux (nitf.ntflux) on surfaces 2, 3, 4 . How to find the boundary equation setting in the new versions 4.4 Send Private Message Flag post as spam. The IP address of all posts is recorded to aid in enforcing these conditions. Heat Transfer & Phase Change That boundary condition accounts directly for heat loss from the solid through conduction and the fluid flow that results accounts for convection. For users of the Battery Design Module, COMSOL Multiphysics version 6.1 introduces a new interface for modeling multiple batteries, the ability to simulate heat transfer in battery layers, and the addition of the Parameter Estimation study step. Is there a way to go about this? You agree that you will not use your COMSOL Access account in violation of any applicable export control laws. I noted that I should use internal boundary to define the non-slip boundary . If you want to add heat flux on internal boundary you can use boundary heat source node." It worked for me. 1 Reply, Please login with a confirmed email address before reporting spam. Edgar. COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH), Using the Inflow Boundary Condition in Nonisothermal Flow Simulations, Modeling Natural and Forced Convection in COMSOL Multiphysics, Derivative Boundary conditions for heat and mass transfer, How to Make Boundary Conditions Conditional in Your Simulation. It works well, except for the boundary conditions. I have tried the open boundary as well as symmetry conditions but in both cases there seems to be no conduction outside of the model. listed if standards is not an option). The simulation for the heat transfer is quiet good but the not in the mass transport. Posted . Heat Transfer & Phase Change Thanks. In order to make this an efficient and pleasant experience for you and other members of COMSOL Access, we ask that you follow a few rules and guidelines. I am trying to simulate the behaviour of optics components when being cooled down from 293K to 4K.I am using Solid Mechanics and Heat Transfer to Solids, where i am applying they temperature to all boundaries. That boundary condition accounts directly for heat loss from the solid through conduction and the fluid flow that results accounts for convection. Heat Transfer & Phase Change Capitalize correctly. Be concise and articulate as much as possible. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help. If my explanation is correct, how to resolve this issue? Discussion Closed This discussion was created more than 6 months ago and has been closed. Should you use a COMSOL Access account associated with an employer, you agree to immediately discontinue using that account upon termination of that employment. To start a new discussion with a link back to this one, click here. You agree to maintain your COMSOL Access account for use solely by you, not to share your username and password with anyone else, and to take appropriate precautions to restrict access to your username and password from others. The COMSOL Access administrators will reserve the right to permanently remove a user account without notice if any of the rules are not followed. rgds Is there any other way to do this so that the heat loss can be included in the analysis? Veryst Engineering, Dear Nagi, The moderators reserve the right to remove, edit, or move posts at their discretion. my model is solid with heat flux on the upper face and fluid moving under the lower face , I used Conjugate heat transfer If you have your metal bar in a flow of helium and want to model the removal of heat by convection then you need to make a boundary for which that helium will be flowing through. The Periodic Condition node adds a periodic boundary condition. What I would like to inquire right now is the problem on the heat loss due to evaporation. The constraint is formulated as ht.T0-ht.Tvar, which . I think I am mis-using a boundary condition but I am not sure. You agree to comply with all rules applicable to each service you access through your COMSOL Access account. that once rearranged this means: Learn about these updates and more below. If you are familiar with LaTeX, please use this to write mathematical equations. Hi, can I give a absorbing boundary condition for a transient heat transfer problem. Loud; laissez un commentaire; Boundary conditions in heat transfer. Cheers Version 5.5 You can fix this by pressing 'F12' on your keyboard, Selecting 'Document Mode' and choosing 'standards' (or the latest version Hi. Your internet explorer is in compatibility mode and may not be displaying the website correctly. When posting, understand that you are trying to communicate with other people. It is difficult to read posts that are written entirely in uppercase or lowercase. Please read the discussion forum rules before posting. h_htgh* (Tinf_htgh-T) + q0_htgh. Solving Models with Step Changes to Loads in Time, Applying boundary condition on imported mesh, Modeling Laser-Material Interactions with the Beer-Lambert Law. 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. In my simualtion the thin film is irradiated by a laser beam, and the substrate is transparent to the wavelenght. For example, you may have a tube in which the helium will flow through and inside that tube you will have your heated metal bar. Here are some important guidelines of language: By submitting content to the forums, you hereby grant COMSOL a nonexclusive, royalty-free, perpetual, worldwide, and unrestricted license to reproduce, publicly display, publicly distribute, and prepare derivative works of the content. Anyway, I'll just leave it at that for the moment. COMSOL hereby grants you a license to copy and/or use content from the forums solely for your own internal purposes. Posted 18 mai 2018, 19:20 UTC+2 Heat Transfer & Phase Change 0 Replies . I am solving for transient case for total time of 300secs with time step of 0.1sec [free time step (not strict)]. We investigated the dynamics of nanofluid and heat transfer in a three-dimensional circular annular using the turbulence model and energy equations. mohamed farahat . Check the application library model in Heat Tranfer Module > Tutorials Conduction > carbon_fibers_infinite_elements to learn how it works. The basic heat transfer in two solids of material iron. Hi everybody, It worked well when there is only bioheat physics, but when i use . I am somewhere stuck up in meshing part, thus, request you to please reply. Jun 11, 2009 #5 mherna48 43 0 You acknowledge that all posts made to these forums express the views and opinions of the author and not the administrators, moderators, or webmaster (except for posts by these people). You might have found out by now, I hope so, but in anycase, in the boundary condition Heat flux you have 2 variables Q and h, you might either choose one or the other, or both. absorbing boundary condition for heat transfer problem. you can use infinite elements. Its fine that comsol itself taking care of interface boundary condition as heat loss from the solid. Once you have selected 2D "htgh" BC's "Heat transfer" and the boundary of interest go to : Beat regards, If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base. you can use infinite elements. Hi everyone. Physics - Equation Systems - Boundary Settings What does it mean? listed if standards is not an option). 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 am using comsol 5.3a version It works well, except for the boundary conditions. Is there an alternative way to assign a surface radiation boundary condition? You can fix this by pressing 'F12' on your keyboard, Selecting 'Document Mode' and choosing 'standards' (or the latest version The purpose of language is to be understood. The passing of the heat air to the surface of the solid boundary caused heat and mass transfer at the same time resulting to some degree of heat loss. In the tutorial (@ 11:49) the narrator assigns a "Surface-to-Ambient Radiation" boundary condition on the outer surface of the model (screen shot attached). Animation of the temperature distribution as the prescribed temperature spot travels along the bar. Am I doing it correctly? Your Discussion has gone 30 days without a reply. It worked well when there is only bioheat physics, but when i use . I want the boundary to simulate the material being continuous outside of the model. Although many COMSOL Access members are not fluent in English, the official language of this forum is English. Hence the Q variable (or q0_htgh internally) enters directly thermal power onto the boundary, while the "h" is proportional to the temperature difference (in K) of (Tinf-T) and T is the temperature you are solving for, so Tinf yould be your constant blood temperature, then h should be scaled to take into account . Posted May 1, 2020, 6:00 a.m. EDT Because I want to consider the heat loss, I tried adding the convective cooling. I need an immediate help for the thread : www.comsol.com/community/forums/general/thread/34647/ The new Thermal Connection multiphysics couplings are designed to define a continuity condition between two temperature fields, computed by a domain heat transfer interface and a Heat Transfer in Shells interface, respectively. listed if standards is not an option). is this right to assign heat fkux and temperature for the same surface? This is to avoid the heat wave reflecting at the boundary and contributing to the temperature rise. Your internet explorer is in compatibility mode and may not be displaying the website correctly. The Equation View for the Temperature node.. This involves providing you with access to technical support and downloads of the latest {:comsol} software releases, as well as the ability to share your comments and work with other users of the {:comsol} software through forums such as the blog, discussion forum, and Application Exchange. Eman Salman . in doing so you, for the purpose of analyzing heat transfer efficiently comsol multiphysics software is one of them which has been taken as a helpful tool for making analysis on the processes of heat transfer in this thesis the author introduces comsol multiphysics software and analyzes heat transfer processes, burlington vt comsol inc 4 / 16 The moderators of the forums will remove any generally objectionable material as quickly as possible. Engaging in any activity in violation of these COMSOL Access rules and guidelines may lead to you being immediately and permanently banned from COMSOL Access. However, in my version, this option is . Format your post in a legible manner. I'm using COMSOL 5.3 to simulate laminar flow in a microchannel that has few internal closed features inside. 11 Replies, Please login with a confirmed email address before reporting spam. Modeling Natural and Forced Convection in COMSOL Multiphysics, Calculating the Heat Transfer Coefficient for Flat and Corrugated Plates, Using the Inflow Boundary Condition in Nonisothermal Flow Simulations. The COMSOL model calculated CBL height, TBL height, and MTC scales with v bulk raised to the-0.44,-0.50, and 0.38 respectively. As a user of COMSOL Access, you agree to any information you have entered into any of the forums being stored in a database. Posted May 12, 2022, 2:53 a.m. GMT+2 You also agree to maintain the accuracy of all information associated with you on your COMSOL Access account. There is no need for a different thermal boundary condition there. Check the application library model in Heat Tranfer Module > Tutorials Conduction > carbon_fibers_infinite_elements to learn how it works. ,but the result show that there are no heat transfer between solid and liquid!! "The heat flux can only be use for external boundaries. April 22nd, 2019 - Heat Transfer Module Updates For users of the Heat Transfer Module COMSOL Multiphysics version 5 3 includes new functionality to model heat and moisture transport in air a new solver for modeling heat transfer in the It works well, except for the boundary conditions. COMSOL provides the forum service for the benefit of our users to share content with the community. The data agrees with the Sherwood and Blasius correlations, however. To start a new discussion with a link back to this one, click here. Hence, they will not be held liable. Nagi Elabbasi There is no need for a different thermal boundary condition there. Hello, I am using COMSOL 5.3a and solving a 3D model using the conjugate heat transfer, laminar flow study. However, there are some important situations where this is not the case, and an Inflow boundary condition can improve the model accuracy and reduce . Particular services accessible with your COMSOL Access account may be subject to additional rules. Neither COMSOL, the authors, nor the copyright owners of submitted materials warrant that the programs will be error-free, uninterrupted, virus-free, secure, and suitable for your needs, produce specific results, or that errors or failures will be corrected. I should get a maximum temperature in the fluid domain not in the solid domain because of higher light absorption characteristic of fluid. My model is similar to the tutorial here. Hi all Ishant Jain, Dear friends When registering for COMSOL Access, you agree to provide your complete and truthful information for all fields requested on your COMSOL Access account registration page. Replying my own question in case it helps others. much better if you upload your file for the other members to comment and have their suggestions. Ivar. Try to avoid using text speak, net speak, or slang. listed if standards is not an option). 4th row (for "T" as the 4th dependent variable u,v,p,T,J), you should see something like: There is no need for a different thermal boundary condition there.

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