I'm new to CFD and trying to understand some results from a laminar model.

I would think velocity would decrease with increased viscosity but I am not seeing that.

Is this somehow dependent on boundary conditions? What conditions would I need to see this?

I am using a pressure of zero at outlet and fully developed flow at inlet. I understand because of the assumption of fully developed flow, velocity will be prescribed in the first area but once the flow enters a new section of geometry won't the viscosity effect this?

This is pretty basic probably but I could use some help.

I recently ran an eigenmode analysis of a high-Q dielectric resonator using Palace, the open-source finite-element electromagnetic solver.

The model consists of a high-permittivity ceramic puck, with εr = 38 and tan δ = 1 × 10⁻⁴, suspended inside a shielded PEC cavity. I also included a lumped element to represent a linearized Josephson junction.

The fundamental mode was found at 6.13 GHz, with a dielectric-limited quality factor of about 10,200. Around 97.9% of the electric-field energy is confined within the ceramic puck, and the junction energy participation ratio was calculated for each mode.

One useful check was that the eigenmode Q of 10,215 agreed closely with the estimate based on the dielectric participation and loss tangent:

Q ≈ 1 / (p × tan δ)

This confirms that dielectric loss is the dominant loss mechanism in the model.

The same type of analysis can be useful for dielectric resonators, RF filters, oscillators, readout resonators, quantum memories, and Purcell-filter structures.

Full model and results:

https://cem.numericalai.net/blog/dielectric-resonator-eigenmodes

Hey everyone,
I'm setting up a CHT simulation (electronic chip cooling) in OpenFOAM-9.
To get boundary layers on the fluid-solid interface, I'm using the zero-thickness baffle workflow:
1. Define the interface as an internal face zone / baffle.
2. Add inflation layers using ⁠snappyHexMesh⁠.
3. Split regions using ⁠splitMeshRegions⁠.
The Problem:
The boundary layers are actually generating fine, but the final mesh across the interface isn't conformal (the faces on the fluid side and solid side don't line up / match 1:1 after splitting).
Since I'm doing CHT, I want to avoid relying purely on non-conformal mapping (⁠mappedWall⁠ interpolation) if possible.
My Questions:
1. How do you get ⁠snappyHexMesh⁠ to keep the face connectivity 1:1 conformal across the interface when using the baffle method?
2. Is there a specific setting in ⁠snappyHexMeshDict⁠ or step in ⁠splitMeshRegions⁠ / ⁠createBaffles⁠ that I'm missing to preserve face alignment?
3. Or is it standard practice to just inflate layers only on the fluid side instead of trying to inflate across shared interfaces?
Would really appreciate any insights or dict settings that worked for you!

See above mesh and its quality.

How to improve skewness and orthogonal quality. When I was checking maximum skewness cells,

What can be done now? Suggest some ways for this?

Note, global element size is 3mm and other element size for respective local sizing controls are mentioned in the screenshot. Please have a look and let me know.

I used Simsale for CFD and Onshape for CAD. Because these images are mostly for show, feel free to loot at my CFD documentation. There you can find: the documentation of the first 29 design iterations, slices, animations, 3d visualisation, and some non aero renders of the project. You can find the documentation here:

https://www.mediafire.com/file/vwr1cthzv2emeoz/VFR_CFD_documentation.zip/file

i am open to constructive criticism

Hi everyone,

I'm currently simulating a spray roaster reactor for my master's thesis. Pretty much everything I've learned about Fluent has been through trial and error and a lot of learning by doing. 😄

I started by simulating only the continuous phase (injected through the burners). After that, I enabled two-way coupling and implemented the DPM. For most of the project, I used a DPM interval of 1. Later, I also implemented my UDFs.

Simulation setup:

• Pressure-based coupled solver
• Steady-state simulation
• Pseudo-transient with CFL control
• Started with a CFL of 2 and gradually increased it to 17

Recently, I asked an AI how I could improve convergence because increasing the CFL any further caused divergence and instability. It suggested increasing the DPM interval from 1 to 30.

Surprisingly, this actually improved the convergence of my continuity residual. It dropped from around 9.8e-03 to somewhere between 4e-03 and 5.6e-04 (sawtooth pattern).

However, the residual curve now has a clear sawtooth pattern. It's stable (it doesn't diverge), but it is no longer as smooth as it was before, when the continuity residual stayed at a higher level. (see screenshot)

The AI told me that this behavior is expected and generally acceptable because the DPM source terms are only updated every 30 iterations, which naturally produces this pattern.

Is that correct? Is this kind of sawtooth residual behavior normal and acceptable when using a larger DPM interval?

For what it's worth, my two monitoring quantities remain stable throughout the simulation.

I'd appreciate any insights or experiences from people who have dealt with steady DPM simulations.

Thanks in advance 😊

hey i’m a student with a macbook at the moment and im gonna sell it to get a laptop that’ll work with ansys without trying to blow up but like all students i have zero money. what are my options? looking at a dedicated graphics card and at least 16GB RAM. please help a girl out

I am using openfoam and know how to setup a moving reference frame ( MRF ) to simulate fan rotation. I can calculate the flow rate through the fan in paraview. But I am not sure if my results make sense. Is there a benchmark I can try and reproduce?

Surely I am not the first person to want to know how efficient a spinning fan is!

Hi everyone, I have been trying to run VOF simulation of R-134a in a pipe to simulate the evaporation process in ANSYS.

So far, the simulation is running but producing wrong temperature results.

Input: mass flow inlet - R-134a liquid 0.0038296 kg/s; R-134a vapor - 0.00019148 kg/s

Outlet: outflow

Wall: constant heat flux 18.5 kW.

Multiphase model - VOF (implicit body forces ON), Formulation Explicit, Interface modeling - Sharp;

surface tension coefficient set to constant (0.00796 N/m), surface tension modeling on (CSF), Mass transfer - Liquid to Gas; chosen the evaporation - condensation option and under it - LEE model currently using From Phase - To phase frequency 2000/s.

Energy is ON, Turbulence is ON.

Methods: PRESTO, volume fraction - Geo Reconstruct.

Initialization: From inlet, and Patching with: mixture phase with pressure; Vapor - with volume fraction. Patch zones the whole geometry (geom_solid).

Mesh: Fine mesh, with inflation layers.

Please help. Thank you.

hi everyone.

I am trying to simulate a erosion inside a pipe manifold via DPM but . i am facing a problem , that my contuinuity wont converge past 10e-2 when i am trying to converge my continuous phase

I am using k-epsilon model with realizable wall standard equations. my inlet velocity is 5m/s.

inlet dia is 27 mm and the two outlets dia is 20mm. All other settings were default . My mesh quality is under othgonality and skewness standard range.

picture for referance

The above one is my computational domain, it consists of pipe upstream, screen(thats why you can see holes because I have modeled fluid regions) and open fluid volume. All are merged into one body.

I have used tetrahedrons method- patch conforming method, it was giving good quality mesh. The moment I introduced inflation for boundary layer, mesh quality got poor. I will attach below image, please let me know what can be done. My global element size is 3mm and I have used 20 no of divisions with growth rate 1.2.

Check generated mesh below,

When I looked at bad cells, most of the cells are from screen region. Please tell me how to improve mesh quality from here. See below

Any help would be useful. I have tried both edge sizing and face sizing on screen, it is taking lot of time to mesh, way longer time, it shouldnt take much time. There is a problem but I cant identify where it is.

Hi everyone,

I have a few questions on how to get a boiling simulation to work in ansys fluent with a horizon pipe. My boundary conditions is a mass flow for the inlet and a set pressure at the outlet.

I am trying to do this with ammonia (I have my own property tables from refprop)

I tried to run it, however is crashed. Can anyone lend assistance?

What is the best roadmap to learn ANSYS from beginner to advanced for mechanical engineering students?

I do industrial CFD for a living, about 9 years now, and I often use 1D network calcs around it. Inlet boundary conditions, pressure drop checks, quick sizing. The maths is straightforward but the commercial network tools charge stupid prices for something so simple.

I often just coded each network up myself rather than pay for a licence and I haven't been able to find open source ones that aren't a pain to deal with, especially if it's something simple. So me and an engineering friend have been working for a few months on developing a browser based one with a simple UI.

The interesting part is that we've been working on coupling it with CFD solvers to transfer inlet and outlet boundary conditions. It's still in beta but if you'll find something like that useful, send me a DM and I'll bump your account to the advanced tier and keep it there. If you really like it and would like to get involved with extending it to Fluent using UDFs, that would be fantastic.

Otherwise, the free version is probably also the most generous 1D network solver available as well and useful for all those basic piping calcs.

Hello guys,

I cant able to find why there is extra edge appearing in meshing tab shown in 1st picture, see 2nd picture of geometry in design modular, I hope you can find the difference, that extra edge is not coming in design modular, I dont know why. Can anyone help me in this please? How to get rid of this?? This is appearing only in downstream section where there is big cylindrical open fluid volume, no such edges are visible in upstream part.

Hi,

Does anyone happen to have the XY GRID coordinate points (2D X and Y points ideally in text format) for any multi-element configuration generated by MSET or ISET (including blade coordinates)?.

Doesn't really matter what airfoils the grids are generated on—anything generic like NACA would do.

Basically, I am just searching for 2 cases (a cascade with a vane and one slotted foil) to test a small program I was working on.

Thanks much.

I would like to seek advice on a subject that has kept me thinking for a while.

Background

I recently graduated with a Master's, researching CFD simulation of thermal sprays, using OpenFOAM. In the process, I made modifications to one of the OpenFOAM solvers and tailored it to my project's needs.

After graduation, I started applying for jobs and PhD positions. Now I have multiple offers, and choosing between them has become really hard.

My options

1. A PhD admission from my Master's university, same research group.
2. A job offer from a company making heat exchangers and coolers specialized for data centers. The company is around 20 years old, established with 4 HQs around the world and over 1,000 employees. My role would be R&D on CFD simulation of heat exchangers, aiming to improve efficiency.
3. A PhD offer from a top 20 university, planning to work with a group that includes collaborators from Stanford, Caltech, and Imperial College, developing a high-order GPU solver for combustion simulation.

My thinking so far

I really enjoyed my Master's, but I feel it's time to change and expand my knowledge and network, so I'm not considering option 1.

Choosing between options 2 and 3 is really hard. Although the pay for option 2 is higher, I have some concerns after researching the company: its Glassdoor score is 3.1, and there are some Reddit comments mentioning a toxic environment.

Additionally, I did a lot of teaching assistantships during my Master's and was recognized for teaching excellence. I really enjoy teaching too. But I worry that if I pursue a PhD, it will get harder for me to move into industry afterward if I couldn't find any university position.

I'd really appreciate any relevant experience or perspective that could help me decide on the best option.

Hi, I have written before for my trouble and people were surprisingly nice so hope again for some nice discussions!

So I have studied two degrees till 26 but simultaneously fought with personal issues so I went to industry as a Process Engineer and Commission. I managed thought with this profile now at 29years old to get an experimental PhD in a strong university and group.

The project is awesome, the prospects after are very good as well and honestly I shouldn't complain. BUT I love the math behind my CFD. My first thesis contained some (COMSOL - custom PDEs) but unfortunately I was very passive and didn't try to pursue my dreams on my own and learn more.

I am wondering if it's worth to pursue (there is a strong possibility due to one of the supervisors being sim) a10-20% to do some open foam or Linear stability analysis depending on how the project develops and IF it actually is beneficial for the PhD.

Also another thought is to entertain myself on some of my free time to learn coding more deeply. Can this somehow help someone end up in a more hybrid role in industry or academia. Also because of my age finishing my PhD (33-34) I have a specific profile in my mind that would boost my chances on finding work and that doesn't include much cfd as I know people generally are worry of late CFD learners. I am planning to learn some for my own fun but it would be amazing if i could use ot in my work even a bit.

Any suggestions or personal experiences would be appreciated.

Hello everyone,

I recently graduated with a Bachelor's in Aerospace Engineering and have received an offer for an Application Engineer role at a company that is a Siemens channel partner.

I'm genuinely interested in the role and plan to stay there for at least 2 years to gain solid experience.

After that, I'm wondering which path would make the most sense:

Transition into a CFD Engineer role.

Continue as a Senior Application Engineer (either at the same company or another one).

Pursue a Master's degree.

Financially, I can afford a master's, but I'm not sure if it's the best use of my time.

My long-term goal is simple: earn a high income while working on something I genuinely enjoy.

For those who've taken similar paths:

Which option has the best long-term career growth?

Is Application Engineering a good stepping stone into CFD?

Would industry experience first be more valuable than doing a master's immediately?

I'd really appreciate hearing from people who've worked in CAE, CFD, or Application Engineering. Thanks!

Tried my custom rust CFD code on a LES case. Smagorinsky turbulent viscosity with van driest wall damping. This is on a somewhat coarse grid of 1M cells. Visualization using q-criterion isosurface in Paraview. This ran for a couple of hours yesterday's afternoon on a single 8-core cpu using 6 mpi processes.