Boundary conditions in heat transfer. I want the boundary to simulate the . Thanks. Always do a quick check for spelling/grammar mistakes. There is no need for a different thermal boundary condition there. 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. Whilst the heat source is active the model heats, then it holds at the max temperature instead of dissipating the heat. The max temp is obtained at the solid domain rather than fluid. Try to avoid using text speak, net speak, or slang. This is to avoid the heat wave reflecting at the boundary and contributing to the temperature rise. In cases where the temperature of the fluid at an inlet is a known quantity, a Temperature boundary condition can be used. Version 5.1 You just need to add the volumetric heat source to fluid and solid domains separately. listed if standards is not an option). 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. is this right to assign heat fkux and temperature for the same surface? COMSOL imposes temperature continuity at the fluid-structure boundary in a conjugate heat transfer problem. Maybe there are some issues on the type of mesh that I am using. The moderators of the forums will remove any generally objectionable material as quickly as possible. Use the Preview button often. Solving Models with Step Changes to Loads in Time, Applying boundary condition on imported mesh, Modeling Laser-Material Interactions with the Beer-Lambert Law. You can fix this by pressing 'F12' on your keyboard, Selecting 'Document Mode' and choosing 'standards' (or the latest version The condition can be set on a boundary shared by the two interfaces or on two boundaries facing each other. Replying my own question in case it helps others. COMSOL imposes temperature continuity at the fluid-structure boundary in a conjugate heat transfer problem. I am using a fixed constraint boundary condition on the surface where the part . How to find the boundary equation setting in the new versions 4.4 The Periodic Condition node adds a periodic boundary condition. Check the application library model in Heat Tranfer Module > Tutorials Conduction > carbon_fibers_infinite_elements to learn how it works. I need an immediate help for the thread : www.comsol.com/community/forums/general/thread/34647/ There is no need for a different thermal boundary condition there. My model is similar to the tutorial here. Heat Transfer Boundary Condition. 4th row (for "T" as the 4th dependent variable u,v,p,T,J), you should see something like: It is difficult to read posts that are written entirely in uppercase or lowercase. ,but the result show that there are no heat transfer between solid and liquid!! Anyway, I'll just leave it at that for the moment. 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. I think I am mis-using a boundary condition but I am not sure. 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. Nonisothermal flow combines CFD and heat transfer analysis. If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base. But , results shows exactly opposite. Boundary condition for heat transfer. Thank you. 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. 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. Posted May 1, 2020, 6:00 a.m. EDT The heat source is only active initially, and I would expect the model to reach thermal equilibrium with the surroundings/boundary conditions. You can fix this by pressing 'F12' on your keyboard, Selecting 'Document Mode' and choosing 'standards' (or the latest version It works well, except for the boundary conditions. Please read the discussion forum rules before posting. In my simualtion the thin film is irradiated by a laser beam, and the substrate is transparent to the wavelenght. Ishant Jain, Dear friends Your Discussion has gone 30 days without a reply. 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. You agree not to post or link to any material that is abusive, obscene, vulgar, slanderous, hateful, threatening, sexually oriented, or that infringes upon or violates any third-party rights or any other material that may violate any applicable laws. Two physics (bioheat physics and moving mesh physics) are included in model to simulate a laser ablation over a part of the bone. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help. 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. You agree to comply with all rules applicable to each service you access through your COMSOL Access account. please help me 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. I want the boundary to simulate the material being continuous outside of the model. I need to impose a user defined boundary condition at the surface of the solid which is in contact with the coolant. The pipe was settled vertically . Cheers Hi all h_htgh* (Tinf_htgh-T) + q0_htgh. Review your post before publishing it. The heat source is only active initially, and I would expect the model to reach thermal equilibrium with the surroundings/boundary conditions. I noted that I should use internal boundary to define the non-slip boundary . Nagi Elabbasi Your internet explorer is in compatibility mode and may not be displaying the website correctly. Your internet explorer is in compatibility mode and may not be displaying the website correctly. In the Joule heating module (2 D), I want to know what are the boundary conditions required for the temperature rise in nanowire, when 1 mA current is passed through the wire having cross-sectional area150 x 150 nm^2 and 5 micron length. What does it mean? The heat flux through internal boundaries can be automatically computed. Anup, Hi Anup, Its fine that comsol itself taking care of interface boundary condition as heat loss from the solid. These rules are subject to change. I am solving for transient case for total time of 300secs with time step of 0.1sec [free time step (not strict)]. 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 managed to get results, but am not quite satisfied yet. Heat Transfer & Phase Change and take alook at i.e. Ivar Kjelberg COMSOL Multiphysics(r) fan, "retired" but still part time CSEM SA (CH) Send . . My model is similar to the tutorial here. Anup, Daer Nagi "The heat flux can only be use for external boundaries. Send Private Message Flag post as spam. Heat Transfer 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. 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 . 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 . Your internet explorer is in compatibility mode and may not be displaying the website correctly. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help. anup, [QUOTE] Thanks. 11 Replies, Please login with a confirmed email address before reporting spam. Got my help from Comsol tech support. Hi!! Hi, can I give a absorbing boundary condition for a transient heat transfer problem. you should have a look, it's excellent for your type of activities (I just got it a week ago) Veryst Engineering, thanks .thanks a lot. "" COMSOL Multiphysics App . 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. 0 Replies, Please login with a confirmed email address before reporting spam. That boundary condition accounts directly for heat loss from the solid through conduction and the fluid flow that results accounts for convection. That boundary condition accounts directly for heat loss from the solid through conduction and the fluid flow that results accounts for convection. 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. Nagi Elabbasi 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 Am I doing it correctly? I knew that in v3.5 it was physics>equation system>boundary setting. That boundary condition accounts directly for heat loss from the solid through conduction and the fluid flow that results accounts for convection. 0 Replies, Please login with a confirmed email address before reporting spam, Dear all You can fix this by pressing 'F12' on your keyboard, Selecting 'Document Mode' and choosing 'standards' (or the latest version For example, write "COMSOL Multiphysics" and not "CMP". please help in this regard. A heat flux boundary condition was executed at the inner cylinder of the annular. Your internet explorer is in compatibility mode and may not be displaying the website correctly. 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. listed if standards is not an option). Version 5.5 I am somewhere stuck up in meshing part, thus, request you to please reply. However, I am having some problems because the boundaries of the grains are inactive (Attached picture). 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.

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