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That's a very difficult question, and I can only give you a rough answer: Snappy Hex Mesh is part of CfdOf, you can use Snappy Hex Mesh as part of CfdOf. Importing "external" meshes (e.g. from Ansys) is not so easy, because the boundary conditions are also processed when the mesh generator is started. This means: You can import an external FEM mesh, but you will have great difficulty setting boundary conditions for it. I have looked into this problem, but have not found a solution. But that does not mean that there is no solution, I am not an expert on this topic, please ask this question in the FreeCad forum, there you will find many experts who can answer your question. You can find the FreeCad forum here: forum.freecad.org/viewforum.php?f=37

I recommend you to ask questions about Linux and Ubuntu in the FreeCad forum. There you will find many experts who work with Linux and will give you help. You can find the FreeCad forum here: forum.freecad.org/viewforum.php?f=37

Your question is a little difficult to understand. I have the impression that you have not yet looked closely at the boundary conditions of OpenFoam. There are many boundary conditions in OpenFoam, including inlet, outlet and open. OpenFoam is a numerical solver, and boundary conditions must be defined in order to perform the simulation. My suggestion: look closely at the boundary conditions of OpenFoam, then you will find the answer to your question.

​@@techbernd5535 I know the part about the boundary conditions. However, my question is why the top part of the fluid region that I set as Outlet does not exit the boundary and appears to be blocked inside.

Thank you very much for your question. May I kindly ask you to post your question in the FreeCad-Forum (forum.freecad.org/viewforum.php?f=37)? In the FreeCad-Forum, you will find more experts who can answer your question. When posting your question, please also write your OS (Windows 10, Windows 11, Linux, ...) and the FreeCad-Version and the CfdOf-Version you are currently using.

Could you please write your question in understandable language? What exactly would you like to know? Furthermore - as I have written many times - the comment function on TH-cam is not suitable for questions. It would be better if you asked your question in the FreeCad forum.

Hello tanushkareddy, the way to mesh a 2d surface has changed one year ago: The 2D meshing is now defined as a "mesh refinement" (=> extrusion). For further information, you can take a look in the Freecad-Forum: forum.freecadweb.org/viewtopic.php?f=37&t=66741

Here's how to do this: * Follow the instructions until 14:05. * In the mesh panel, select gmsh (polyhedral) and base element size 2.5 mm, as shown in the video. Click "close". * With the mesh selected in the model tree, click the "mesh refinement" button (icon is a circular object with some elements colored green). Select "extrusion", then "2D planar mesh", and set thickness equal to 30 mm. Add the back face to the reference list by selecting it in the model, then clicking "Add". Click "OK" to exit mesh refinement. * Double-click the mesh (probably called "Body_Mesh") in the model tree to re-open the mesh panel. "Write mesh case", then "run mesher". Finally "load surface mesh" so you can see it inside FreeCAD. Click "close" to exit this panel. * Your water rectangle needs to be inside the mesh, but the mesh probably extruded in the wrong direction. An easy workaround is to go into "Part Design" workbench, double-click the pad for the water, and in the pad menu select "reversed". Click "OK". The rectangle should now be inside the mesh. * Skip ahead to 16:40. If you accidentally created boundary conditions when following 14:05-16:40, remove them.

@@mechiejessie Thank you for your advices! I followed your instructions step by step (I reversed only the pad for water so it is inside the mesh, I didn't define boundary conditions) and finally (after many years😅) I had a working simulation (with BlueCFD and ESI in Windows 10, with BlueCFD in Ubuntu 22.04). Thank you so much! 😊 Of course, thanks to Tech Bernd, your tutorials are precious😁

This seems to be a problem with the part design workbench. As mentioned several times before, youtube is not the right medium for questions like these because a) you do not have the possibility to upload the file and information about your system b) only one (=me) can answer your questions. The right medium is the FreeCad-Forum. In the FreeCad-Forum, many experts can answer your questions. Here is the link to the FreeCad-Forum: forum.freecad.org/index.php

@@techbernd5535 Thank you

Tut mir leid, dazu kann ich Dir keine Antwort geben. Es hängt vermutlich mit der Konfiguration Deines Rechners und vor allem mit der Parallelisierung zusammen. Diese Frage ist besser im FreeCad-Forum aufgehoben, hier können Experten, die sich deutlich besser mit der Konfiguration auskennen, Deine Frage beantworten. Im FreeCad-Forum findest Du auch meine Eingabedatei. Den Unterabschnitt CFD im FreeCad-Form findest Du hier: forum.freecad.org/viewforum.php?f=37

The current version of FreeCad is not 100% similar to the version used in this video tutorial. There have been several changes. One of the changes is that the reference pressures for incompressible mediums / simulations was in older 0, now it is similar to the atmospheric pressure. Advantage: The reference pressure is equal for compressible simulations and incompressible simulations. For incompressible mediums / simulations, the reference pressure has no impact on the simulation results. I hope that I could answer your question completely. For the future, please ask questions like these in the FreeCad-Forum, because there are more Experts to answert. You will find the FreeCad-Forum here: forum.freecad.org/viewforum.php?f=37

@@techbernd5535 thank you for your responses 🙂 and I always find your answers to be excellent. I find you to be an expert. I know the forms have other experts too, but you're pretty good too. I just posted an example of my rocket on the forums and Thomas just replied with a lot of information that I need to go through. I thought I was pretty good at cfd but I'm finding out that I'm missing a lot haha

Questions like these should be asked in the FreeCad-Forum: forum.freecad.org/viewforum.php?f=37

Please ask questions like these in the FreeCad-Forum: forum.freecad.org/viewforum.php?f=37

It would be very advisable if you asked questions of this kind in the FreeCad forum. The structure of the FreeCad forum makes it easier to answer your questions in a structured manner. In the FreeCad forum, not only I, but also the other experts can give you a qualified answer. You can find the FreeCad forum here: forum.freecad.org/viewforum.php?f=37

Sure. You can ask your question in the FreeCad-Forum: forum.freecad.org/viewforum.php?f=18

The version of FreeCad is 21.2 and that of Openfoam is v2212

Thank you very much for your question. The place for general questions about FreeCad and FreeCad CfdOf is the FreeCad Forum: forum.freecad.org/viewforum.php?f=37 and forum.freecad.org/index.php. For questions like your questions, this forum is better suited because you can upload your files.

th-cam.com/video/EsKJ7LBA2fY/w-d-xo.htmlfeature=shared something like this

Hello Satish, if you need professional help, you can ask the FreeCad Forum: forum.freecad.org/viewforum.php?f=31

The simulation of the Couette Flow is shown in this video: th-cam.com/video/Gu5qhZ6UL9g/w-d-xo.htmlsi=-wK4NCUntSBp2aVm

@@techbernd5535 No i think that is the "Couette Taylor flow" and the real Couette flow is in this video over 2 plates

@@eliesmaths4256 : The problem is a bit more complex: The rotationally symmetric problem shown in the linked tutorial is a Couette flow, and here the results of the analytical formula and the CFD simulation agree. The simulation shown in this video is a Couette flow because the outer wall rotates. If the inner wall were to rotate, it would be a Taylor-Couette flow. In the German Wikipedia page on "Scherströmung" (= "shear flow"), two flows are explained: Couette flow and Couette-Poiseuille flow. The flow I simulated seems to be more of a Couette-Poiseuille flow. Link to the German Wikipedia article: de.wikipedia.org/wiki/Scherstr%C3%B6mung#Couette-Poiseuille-Str%C3%B6mung. I have not checked whether the Couette-Poiseuille model works better than the Couette model and whether there is a pressure gradient. At first glance, this flow looks like a Couette-Poiseuille flow.

@@techbernd5535 okay thank you, and with my simulation over two plate I fullfill to obtain the velocity u(y) like the formula of the model thanks to a lower velocity of plate or a bigger viscuosity, because the reynolds needs to be low, so now I have no problem with this simulation.

That is right

Could you please ask your question in the CfdOf-subforum of the FreeCad-Forum? You will find the subforum here: forum.freecad.org/viewforum.php?f=37. In the FreeCad-Forum, you will find many experts who can help you.

Which freecad version are you using? Use version 20.2, do not use 21.

did u solved it? i got same problem too

no, i want to know how to fix that@@JadeConsult

Which freecad version are you using? Use version 20.2, do not use 21.

Your question relates to FreeCad in general. Therefore you should ask this question in the FreeCad forum: forum.freecad.org/viewforum.php?f=37

Looking on the header above the columns, you will please find the labels "total_x, [...], pressure_x, [...], viscous_x, [...]. The "total_x" is the sum of "pressure_x" and "viscous_x". Because the share of "viscous_x" is low, the first and the fourth column are nearly equal.

No, boolean fragments is independent of 2D mesh. I created the 2D mesh by creating the shape in the sketcher-workbench and creating a surface from the lines in the part workbench. "Boolean fragments" were necessary because I needed multiple surfaces: 1 surface represents the air, the other two surfaces represent the magnets. Whenever possible, I prefer 2D mesh in my tutorials because the computing time is shorter and because they are more descriptive. I could also have built this model as a 3D mesh, then instead of the surfaces I would have used either bodies from the part design workbench or bodies from the part workbench. I would also have assembled these 3d bodies using "boolean fragments". The assembly via "boolean fragments" is necessary to get a consistent mesh.

@@techbernd5535 Could you help me with this error report then? """ 18:40:34 Exception in thread Thread-70: 18:40:34 Traceback (most recent call last): 18:40:34 File "E:\Programy\FreeCAD 0.21\bin\lib\threading.py", line 932, in _bootstrap_inner 18:40:34 self.run() 18:40:34 File "E:\Programy\FreeCAD 0.21\bin\lib\threading.py", line 870, in run 18:40:34 self._target(*self._args, **self._kwargs) 18:40:34 File "E:\Programy\FreeCAD 0.21\Mod\Fem\femsolver\task.py", line 118, in protector 18:40:34 self.run() 18:40:34 File "E:\Programy\FreeCAD 0.21\Mod\Fem\femsolver\elmer\tasks.py", line 52, in run 18:40:34 self.check_material_exists() 18:40:34 File "E:\Programy\FreeCAD 0.21\Mod\Fem\femsolver un.py", line 440, in check_material_exists 18:40:34 objs = self.get_several_member("App::MaterialObjectPython") 18:40:34 File "E:\Programy\FreeCAD 0.21\Mod\Fem\femsolver un.py", line 422, in get_several_member 18:40:34 return membertools.get_several_member(self.analysis, t) 18:40:34 File "E:\Programy\FreeCAD 0.21\Mod\Fem\femtools\membertools.py", line 126, in get_several_member 18:40:34 obj_dict["RefShapeType"] = femutils.get_refshape_type(m) 18:40:34 File "E:\Programy\FreeCAD 0.21\Mod\Fem\femtools\femutils.py", line 364, in get_refshape_type 18:40:34 first_ref_shape = get_element(first_ref_obj[0], first_ref_obj[1][0]) 18:40:34 File "E:\Programy\FreeCAD 0.21\Mod\Fem\femtools\geomtools.py", line 189, in get_element 18:40:34 return part.Shape.getElement(element) # Face, Edge, Vertex 18:40:34 ValueError: Invalid subelement name """

Thank you for your interest in my tutorial. You are absolutely right: both boundary conditions are possible for the rear wall. I simulated the "wind tunnel" application, hence the boundary condition slip. The boundary condition “outlet” or “open” should in principle also be possible. Please note that I deliberately chose the dimension of the simulation space to be very small in order to save storage space and computing time. If the simulation space had been chosen to be sufficiently large, the difference between these two boundary conditions should be very small.

In contrast to solids, liquid can only flow under pressure, so there is no pulling. To be more precise, this tutorial actually only calculates the effect of a pressure difference between the inlet and outlet. As long as there is higher pressure at the inlet than at the outlet, the medium flows towards the outlet.

If you need information, please write your request clearly and in detail. In any case, it is better to make this request in the FreeCad forum than here. And please don't use abbreviations. The abbreviation "smae" doesn't mean anything to me, so I can't answer your question. I have recorded 15 tutorials about FreeCad CfdOf, isn't there a tutorial that will help you with your question? You always have to understand the basics first, so my first tutorials will help you before you can tackle more complicated questions.

@@techbernd5535 oh, the word smae was a typo of the word "same" haha. Thats my phones fault. To answer your question "inst there a tutorial that can help you with your question?" There is not, hence why i was asking :) I will start on the freecad forums and go from there. Thank you :)

@@techbernd5535 Here is a request. How to do CFD on a 2d object. IE maybe wind blowing onto a flat plate. Show how to set that up and solve for the force of the wind blowing onto the flat plate. I think that would be a very informative video. thank you: )

@@LT72884 These types of simulations are sufficiently explained in my tutorials. I don't see any reason to record a new tutorial. If you lack the specialist knowledge for Cfd or FreeCad CfdOf, you can get professional help here: forum.freecad.org/viewforum.php?f=31

@@techbernd5535 ill look again through your tutorials to see if i can find one that is a fluid pushing into a plate. Thanks

As I wrote several times, please ask questions like these in the Freecad-Forum. TH-cam ist not the right medium for questions like these and for asking help.

Hi @JustAnotherAlchemist, no problem. Just send me an order for tutorials that suit your taste and I'll record my tutorials again. My cost per tutorial is $1000. Now seriously: I make these tutorials for free. This means that I determine the layout myself. There are certainly quite a few wishes as to what colors FreeCad should have. I can't take that into account. I'm using the "Default Layout" of FreeCad because I assume that the vast majority of users using my video will use this layout. If you would like FreeCad to use a different default layout, please register in the forum and start a new thread. I'm a little older and have problems with readability on dark backgrounds. I can read better when using light backgrounds. Likewise, you shouldn't be interested in the software I used for the explanations. I use the software that works best for me. It's not about software, it's about the content.

Hi @zmedford1, thank you for your question. Probably, my answer in the FreeCad-Forum might help you: forum.freecad.org/viewtopic.php?p=731746#p731746

Oh hey there.

@@baltofarlander2618 Hello there! Are you winning my son?

@@stal_keys Not yet.

As I wrote earlier, the FreeCad forum is better suited for these types of questions. Could you please ask your question there? The link to the FreeCad-Forum, subforum CfdOf, is: forum.freecad.org/viewforum.php?f=37 The expression "Overset mesh simulation" is unknown to me. Could you further detail your question in your post in the FreeCad forum? Which solver does your question refer to? Does your question only apply to InterFoam and mixed fluids, or to all solvers? What application do you want to use this technique for?

@@techbernd5535 Sure I will elaborate my question and post on the foruns during my lunch break, I am not sure, but I believe that it doesn't apply to InterFoam, if I am not mistaken there are a few special set of solvers, the one I have in mind if overDynInterSolver or something like this. The overset mesh is typically used to combine mesh elements. The best example I think is a rotating propeller, because you have the background mesh, that is, the control volume, and you have the propeller mesh, that rotates, pushing the fluid. In my case, I am trying to do a mooring analysis of a safety buoy net. I will apply the fluid velocity on the inlet, try to implement the mooring library to apply the BCs on the floating bodies and see how they behave. I need to prevent the buoy assembly of going underwater under heavy flow when the hydroeletric plant opens its flooding gates.

Hi @poulmack, thank you very much for this interesting question. I had already answered a similar question, but the answer has disappeared. I spend a lot of effort answering questions, so I will no longer answer these questions via TH-cam in the future. The risk of my answers disappearing is too great for me. Therefore, I would like to ask you to ask your question in the FreeCad forum, subsection CfdOf. Other experts, such as oliveroxtoby and thschrader, also have the opportunity to respond there. The address is: forum.freecad.org/viewforum.php?f=37