Hello Everyone, I'm actually simulating the impact of jet on a hot plate, but while showing the results to it my professor he said you don't have enough data to back up your results, he said me to take help of heat transfer to validate Or take help of any research paper. Can anyone help me with this problem. I haven't found any data to on internet also can anyone help me? . I would forever in debt all i get are these videos but i need to validate my data.

Hello all!

I've been tasked with setting up a vacuum chamber simulation, in hopes of getting a gas flow array output using ansys fluent for part of my Ph.D. I've been working on this for a month or so now and just can't seem to get a handle on how to set up this simulation in fluent and get it to work for me. I Would really appreciate any help/advice anyone could provide!

I'm going to include a brief summary of what I've already done, and might end up including some useless information or excluding some important information as I'm not entirely sure what is useful and what isn't (or maybe there are just settings I don't know exist).

I made a file for my vacuum chamber in inventor --> exported as .stl file

Imported .stl into spaceclaim --> used volume extract tool to make a volume for the vacuum chamber, and used the combine tool to combine all the volumes into one volume.

Imported the combined volume into Mesh --> Added three surfaces corresponding to where my gas will enter and exit the chamber from, and meshed my system (2.0 E-3 m meshing)

I then imported the mesh into Fluent and set parameters for my three surfaces corresponding to values previously used in my group by a past student which worked for them. I have two pressure inlets, and one mass flow outlet.

One pressure inlet is a line that would go to a throttled pump with nitrogen flow coming into the system from there. Previously my group has modeled this as a pressure inlet but I'm not 100% sure that is correct. It's just supposed to set the pressure of the larger part of the chamber to a specific pressure.

I defined the "internal" and "wall" as the variables labeled volume and wall from my imported mesh. I'm just assuming air is what is coming in, which is set as my fluid.

If I run the computations it will run for some period of time and during this period of time I get one warning: "Mach number exceeds maximum limit on pressure-outlet-7 for 27 faces bounding Mach number to maximum limit =9.800000e-01". Does this mean I need a smaller mesh size? I would find that strange since I'm using the same mesh size previously used for this chamber.

And eventually it will finish iterating and give me a result that looks unrealistic.

Are there more settings I should adjust before starting the simulation? Is the error I mentioned my issue, how might I go about fixing that? Is there anything I'm forgetting to explain that would be helpful?

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Riemann problem equations with I.C.

Hi all, I am trying to get started with solving this question. I understand it is a 1D nonlinear, coupled, hyperbolic system of conservation laws. Though specifically, is it a gas dynamics systems, or something else. Although it is a close variation of Burger's equation.
I think the steps to solve are:

1. getting the characteristic equation
2. examining the eigenvalues and eigenvectors of the jacobian matrix
3. computing the flux vector
4. determining the type of shock/ rarefaction waves?
5. drawing the constant lines/ curves

I also wanted to know how the Hugoniot-Locus plays a part in these equations.
I really appreciate your help to get me started, and we can make this an insightful discussion.

Hi All,

I am new to CFD and I am doing a aerodynamics module at University.

Using Star CCM I am trying to find the aerodynamic balance of a road car at 120mph. I have found the below formula on website.

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https://preview.redd.it/bg03nvle2uwc1.png?width=1186&format=png&auto=webp&s=c572cf9e70a9abcc58c78502ede95129e7bd406c

Using this method I have run my sim and got an overall lift coefficient of -0.109 and an moment coefficient taken on the rear wheel CenterPoint of -0.261. My wheelbase is 2.575m and the overall ref length of the car is 4.393m.

Using the method above I get an overall result of 408% on the front axle.

Any advice on where I have gone wrong would be much appreciated!

Thanks

I want to get the minimal cell size for my mesh in the axial, radial and azimuthal directions

Hey people,

So I am trying to compare 3D and 2D CFD simulations for a heat exchanger on Comsol multiphysics. 3D is fine because they already have one but in the process of making a 2D model it cuts the shell side and segments it making it unusable. I tried to make two separate models for shell side and tube side but then I won't be able to work out heat transfer coefficient because the fluids don't interact. Any thoughts on this? Tried to use comsol support but they disabled my account lol (using my uni license)

Hi guys, i'm working on an assigment, i tend to do simulation to compare efficient of 2 thermal insulation material between CPU and block of heatsink. Does this would make the assignment is too hard? Should I assump the power cooling? If you have any docs or idea about this, pls share or contact to me. Thanks

what kind of CFD/FEA projects do hardware companies have to outsource?

i am an amateur cfd practitioner/freelancer.

Thanks and regards

Hi, for my university course I am doing a comparitive CFD analysis between the actual geometry of a radiator and a discretised model of the same radiator. I have ran the simulations and have some comparitive results eg. the heat transfer, pressure drop etc., now the whole point of doing a discretised model is to lessen the computation power and designing time needed instead of running the actual geometry each time. So my question is what methods are there/how can I account for the extra losses which are in the actual model which aren’t present in the discretised model. Thanks for the help!

Any integration ideas or other software ideas welcome. BlockmeshDict makes meshes with a single cell thickness. I am not sure how to convert that as purely 2D from 2.5D for ANSYS Fluent from there.

I want to simulate flow structure interactions for a fluid flowing through a pipe without any other factors like gravity. Is that possible? I've been looking at CEL resources and the only thing I see everyone doing is gravitational and hydrostatic analysis. The software I'm using is ABAQUS.

So I’m preparing my PhD defense talk, and I’d sort of like to give a cost estimate in terms of electricity used for some of my simulations. The biggest sim I ran took 9 months on the DOD HPC using 512 CPU cores. Simplest case I ran took about 6 hours on a 20 core workstation. Does anyone know of a way to get a quick estimate of electricity costing per CPU hour? It’s not a make or break sort of thing for me but I think it would help communicate the high expense of WRLES to the audience.

Hello everyone i'm doing some multiphase simulations in which i want my cfl to be less than 1 only for particular region , since there are multiple regions in my file

is there any way i can do this

Type of Reboiler

How do I make the speed streamline diagram on the left? (Velocity vectors and velocity streamlines are shown in the left panel). I can only make the streamline diagram on the right. I would like to know how to display a velocity stream in a plane. I use STAR CCM +

Thank you very much.

https://preview.redd.it/8visqjsb4kwc1.png?width=691&format=png&auto=webp&s=86dab41c9ff887fdd7033f9c8d77276e65b275b5

I am simulating this chamber that contains water vapor at 523K and 1 atm pressure.
The chamber is filled with vapor at the start of the simulation. The aim is to fill it with air until the wall temperature reduces to below 273K.
There are three fans on the inlets with the following configurations (one on each inlet): 100 660m³/h at 14,34mmwc pressure.
On the outlets, there are three exhaust fans, one for each exit with the following configuration:
101 321m³/h at 12,35mmwc pressure.

what would be the best way to model this to visualize the air filling the chamber, and get the best approximation of the temperature on the wall?

https://preview.redd.it/sn9hgh9u6iwc1.png?width=721&format=png&auto=webp&s=a7409c6d48c42dada917c55cf387f7e3c6f5bc2e

New to CFD, just starting to use ANSYS fluent, I want to run a simulation to show how the flow changes in a 3D pipe from laminar to turbulent as the velocity increases? Not sure how to do this, all I can seem to do is select a specific inlet velocity an generate a flow stream.

It happens more than often that i try to clean up and mesh complex geometries on ansys, for example a certain cad i have in Spaceclaim, it won't subtract from the enclosure even if the geometry is perfectly good and simple. Sometimes everything goes well in Spaceclaim but makes errors and warnings in meshing that requires a lot of time and effort to solve.

Most of the time this geometry is easily prepared and meshed on Simscale and i get acceptable quality mesh and converged solution.

Why is that? is Spaceclaim not good enough for preprocessing and geometry clean up?

It's like Simscale is more robust in dealing with the model

So every time I use the poly-hexcore meshing in ANSYS Fluent for external aerodynamics cases, I observe that the polyhedral mesh is also applied to the walls of the enclosure. The whole reason for using this mesh is to utilize hex mesh in the bulk region and polyhedral for capturing complex geometries, then why does the wall of the enclosure get captured by polyhedral mesh instead of being meshed directly by hex as it is just a plain rectangular face?

I have a pipe that starts out straight and then narrows (converges) after a certain distance. Initially, the pipe is filled with air. Liquid nitrous oxide is injected into the pipe at 300 K and 70 bar pressure. As the flow passes the converging section, it accelerates, pressure drops below 50 bar and liquid n2o becomes vapour. The phase change that happened here is due to pressure. Here, three phases are involved (air, liquid n2o, vapour n2o).

How do I approach this problem?

Hi, I have a question how to produce a plot for the Mach number vs. X-location for the j=1 computational cell centers for the exact solution.

I have an array that has three columns titled “Mach cell centers” and has columns xc, yc, and mc. Which I’m assuming is the x, y, and Mach values.

I’m confused in where the j=1 computational cell centers for the exact solution comes into play in plotting this. Any help would be appreciated!

Hello everyone, I want to create an analysis to investigate the effects of vortex generators on NACA 0012. However, when creating the flow domain, the vg parts end yo inside the domain. I can not reach the faces of the vortex generators and i can not give them a named selection. How can i properly create the flow domain or how can i select these parts in Ansys meshing? ( I united the airfoil and vortex generators and then made a substraction to create flow domain.)

I am currently running a langrangian multiphase implicit unsteady simulation to design an aerosol particle splitter (depending on their size). It has one inlet and two outlets. The particles are injected with a log-normal distribution.

I need to get the particles size distribution at the outlets. I managed easily to get it at every time step but I'd like to sum over, say, 10 seconds for example. I want to avoid as much as possible to generate a CSV file at every time step if it is possible.

Thank you for your help.

Does anyone using cfd online now? I am just about to upload my reply with attachments then the site crashes. Not able to open the site. I have tried replying with my friends pc but same thing. But if I open in other pc it is opening. Only me and friend can't open in our pc.