Hi all, new user in Ansys and I am not very sure about some things after several hours of tutorials. I would be very grateful to receive recommendations for the set-up.

My basic project is to theoretically evaluate a venturi tube for flow monitoring and confirm the results with simulations. In the last tutorial I have seen I was able to confirm the velocities with the simulation.

My question starts with the Reynolds number, how do I get the Reynolds number for the whole temperature range from -20 °C to 100 °C with the simulation (analytically I already have it)? According to my data, the flow regime is laminar and goes from 0.00739262 to 141.2523226.

The kinetic viscosity is given at 40 °C and at 100 °C and analytically I have the values for the whole range and the graph is quite close to that of the oil manufacturer. Is it possible to check these values of viscosity with the simulation? the same also for the Reynolds number variation and the friction losses.

As for the velocities, how can I get the velocity profile?

The idea is to simulate it as an ideal problem to confirm my calculations and then as a non-ideal problem.

Thank you very much for any input.

Hello!

I recently made a steady-state FVM Incompressible 2D Navier Stokes solver using the SIMPLE algorithm for a collocated cartesian orthogonal grid in C++ by following the lectures by Sandip Mazumder

For solving the momentum/pressure correction equations, I am using the Gauss Seidel algorithm.

As for the residual calculation, I am using the L^2 norm, adding the error of each node and at the end taking the square root

As far as my understanding of the SIMPLE algorithm goes this is the general structure.

while u, v, p are not converged (outer iteration):
    Solve X momentum (with inner iterations)
    Solve Y momentum (with inner iterations)
    Solve pressure correction equation (with inner iterations)
    Correct stuff

I am going to use the terms initial/final residuals which are explained here

I am calculating the initial residuals as follows:

• Velocity: After the 1st inner iteration of the Gauss seidel algorithm of the momentum equations.
• Pressure: Calculating the mass imbalance after calculating the pressure correction coefficients right before solving the equation.

I am calculating the final residuals as follows:

• Momentum equations: The residual values of the last iteration of the Gauss Seidel algorithm.
• Pressure correction equation: The residual values of the last iteration of the Gauss Seidel algorithm.

At the moment I am only doing 1 inner iteration for each equation and the code converges. Though it seems that nobody is doing it this way seeing diagrams of residuals commercial products create. (maybe because this way the coefficients are calculated more times than needed?) Thus, I decided to start adding more inner iterations and this is where trouble began.

I am solving the momentum equations by reducing the initial residual I calculated on the first inner iteration by an amount of orders (set at 2 orders of magnitude).

As for the pressure correction equation, I am starting with 0 pressure correction everywhere and I am solving with a tolerance of 4 orders of magnitude.

The momentum equations seem to be converging, but something weird happens with the pressure correction equation. Instead of the pressure correction values converging, it seems that the difference between each inner iteration is converging while the correction values keep on getting larger. This is obviously not the expected behaviour. On a closer look, the first outer iteration goes by because it just happens that the difference is within the tolerance, but on the second outer iteration it is pretty clear that something's wrong (which is probably why I got away with just 1 inner iteration).

Have I understood something wrong or is it simply an error in the way I am solving the pressure equation (or the coefficients themselves)?

Any ideas?

Almost all open positions require a bachelor’s degree and 8-10 years of industry experience. It doesn’t seem like they want any PhD as candidates at all. I understand the market is tough right now, but a PhD is generally considered equivalent to 5 years of experience. Which part is special that makes PhD experience useless in electronic cooling?

Hi, I'm working on some simulations in Autodesk cfd 2024 but I've noticed that it's not as fast as it should be, checking ryzen master, it is not fully utilizing the CPU, I've tried running cfd instal.exe and manually set the CPU cores but it is still not even using 30% of the CPU capability.

Thanks for any help

Hi all,

I'm doing an FSI of a wing in Star-CCM+. I am having trouble with this Warning when I run my simulations: Warning: Decoupled fluid structure interfaces detected NACA0015 Wing Solid Region/Fluid Domain [0] and NACA0015 Wing Solid Region/Fluid Domain [1] are decoupled.

I have created a mapped contact boundary/ interface between the solid region(wing) and fluid region. Would anyone have any advice/ steps on how solve this or provide any further insight into what this means. For context I am trying to simulate the displacement of the wing following a disturbance (which I am using a body load).

I am new to fluid structure interaction and have limited experience in Star-CCM+.

Any advice/ instructions on the general topic of creating FSI simulations would also be greatly appreciated, Thanks!!

https://preview.redd.it/cug2kkka7cyd1.png?width=3829&format=png&auto=webp&s=7db70c4e31a245a090e16ca0856f5347359a701c

Anyone out there used Diesel RK software for ICE simulation? I needed to know how to run dual fuel simulation, I mean I don't know how to use Natural Gas and Diesel at a time in the simulation process. Can anyone enlighten me? Any kind of tutorial is appreciated

Currently running a simulation for cavitation. I have setup both a solution history file and a field mean monitor, but I can't seem to get the average value at steady state. I've tried plotting the field-mean as a XY plot, a scalar scene and it shows nothing. I have no idea how to manipulate the solution history to get the time-averaged value.

I was trying to run some 2D flow analysis inside pipe, whenever i execute the mesh, the cells appear deformed and non-uniform no matter how small the cell size is. How can i control mesh distribution over the surface ?

I have been trying to develop a model where there is a set amount of liquid in the bottom of a steel container that is filled with Argon near vacuum. The heat is then brought up to the evaporation temperature of liquid and should vaporize, disperse and be driven up to the top of the container where I want it to condense and collect in a bucket above. I've been trying to use the VOF model, but it is not quite working the way I want.

Any tips? How would you model the multiphase and Argon gas? Any suggestions?

When I tried to run with EMP the solver diverges almost instantly and it seems like the boundaries of the steel container are unable to heat up the liquid. My mesh is really refined and high quality.

When I try to run a simulation on Linux Sever (WSL-Ubuntu) while enabling GPGPU option, it gives me this message:

"warning: using the cuda mps daemon is advised but it does not appear to be running on the following host: administrator

gpgpu performance might be impaired. please check the user's guide for further information about mps."

The simulation is 3D - two phase - turbulent - transient( Implicit Unsteady) (Reynolds Stress Model - VOF)

The GPU is: Nvidia RTX 3070 Laptop, Driver Version 561.09, Cuda Version 12.6. and I had installed the latest drivers versions.

Anyone can help solving this problem?

So, I am pretty new to CFD (took the course in my university this semester)
I am doing a project under my prof for designing a methanol steam reformer (The research paper already exists, it is of the professor under whom i am doing this project), so i had to make design changes in the reformer and study the yield of hydrogen........ I have been trying to simulate it for the past 3 weeks and unable to get the solution to converge..... (PS this is the first time i am putting myself to use Ansys Fluent)
I have tried many changes to my geometry, meshing, and setup, but its not converging
I have a validation solution done by a Phd student (when the paper was written)
I am attaching an image of what the residuals in the converged solutions look like and what they look like for ...... for me the residuals go on to oscillate on and on

If someone can guide me or help me, it would really be cool and helpful for me
(thank you)

EDIT
Problem Statement : To perform numerical study on methanol steam reforming reactor utilizing engine exhaust heat for hydrogen generation.

This is the geometry of the problem Lc = 30mm, Lcb = 100mm(catalyst bed), L = 160mm, Di = 40mm, Do = 80mm, t = 2mm

I have made the geometry in Ansys Design Modeller and meshed it in Ansys meshing
The setup that I am applying is

Energy Equation (On)

Laminar Flow

Mixture Template (CH3OH, H2O, CO2, CO, H2, N2)(N2 is taken as an inert gas)

Species Transport (Volumetric) - I have attached images of the reactions that I have defined (The constants required, I already found them by using the research paper)

There are two reactions defined in the simulation (species transport)

The cell zone conditions are as follows:

1. Reforming Channel : for catalyst bed (I defined a porous zone and the reaction); for the zone before and after catalyst bed, I am defining nothing but the mixture template

2. Exhaust Channel : only "air"

The boundary conditions are as follows:

1. inlet for reforming channel : v = 0.1m/sec, T=453K, X(ch3oh)=0.476, X(h2o)=0.524 (defined as mole fractions)

2. inlet for exhaust channel : v = 1m/sec, T=673K

I believe that the mistake in setup that i must be making has to be in the wall, interface sections of the boundary conditions, as i am unable to understand what to put up there.....

Thank you for helping.

TLDR: Choose between the two laptops i listed below. i just explain in detail how i came to this final choice for context reasons, you can skim past the next few lines of course to save time.

So, i need a laptop for CAD, light CFD loads, and video editing. I do game occasionally, but not a huge factor in the purchase decision. I initially asked in the cfd sub for help and also on the side worked on some basic builds that i had in mind, but i came to a realisation that a PC is not the right choice for me at this moment, i will be moving out of the country too soon and will not be able to take the PC with me, and Mobility is very important for me and remote control is not an option due to connectivity issues in the places i frequent. There are other reasons, but allow me to skip past to keep the post short.

I initially did some looking around online and then went to Dell, HP, Lenovo and Asus stores. I took a list of all the products they had and started narrowing down. CPU and RAM are crucial, so i narrowed down using just two conditions, R9 or i9 processors and min 32gigs with at least ddr5-5200 Mhz. Dell had no options (4800MHz was max ram speed). HP Omen looked good but i found better options for same price or same specs for better price in Asus and Lenovo. This is in India, so the models and specs may vary from those in the US.

So essentially, i need to choose between:

1. ASUS ROG Strix G16, i9 14900hx, RTX 4070 8GB GDDR6, 32GB DDR5-5600MHz, Full specs here if you are interested, for approx $2378 (potentially $1996).
2. Legion pro 5, Ryzen 9 7945HX, 32GB DDR5-5200MHz, with a 4060 8GB for $2122, or a 4070 8GB for $2420. Full specs for 4060 4070
3. Legion 7i, i9 14900hx, RTX 4060 8GB GDDR6, 32GB DDR5-5600MHz, Full specs, for $2134 approx.

I'm an Aerospace Engineering student responsible for the Aerodynamics portion of a Quadrotor drone project. After searching for BEMT software to analyze rotor options for our drones, I found JBlade, which has a graphical interface and includes XFLR5 integrated within it (or so I thought). However, I haven't been able to compile it on my Debian 12 system due to issues with lgqlviewer.

I'm using this GitHub repository - https://github.com/MrTypename/jblade-code. Has anyone worked with JBlade before? Any suggestions are welcome!

What are the CFD softwares which are used to analyze irregularly shaped bridges response prone to hurricanes or like any supertall buildings ?

Hello people, i need help on my optimization project. i have experience when it comes to cfx and fluent. but RL/Ai is new for me, im stuck at how can i do things. gather simulation data to set reinforcement learning environement ect...

We have to start a project using ANSYS FLUENT for CFD project in a thermofluid-experiment lecture.

Any project ideas would you recommend?

It should be something like can be seen in the real-life and explainable with the basic thermodynamics and fluid mechanics and heat transfer.

Hello there! I want to make an easy* multiphase flow simulation between water and air. In this simulation i want to place an boat on it. It is a 2D simulation from the side of the ship. And was wondering if there is any good video tutorial out there.

I would like to use openfoam, but i am open for other suggestions. I am also willing to pay if some other software is easier to use for this.

Sooo: I want to know if there is any good tutorial for this on the interwebs. Any fellow blobs here that can help me? Thanks in advance!

Hi! I need to do some simulations of flow inside a porous domain with a 3d detailed geometry. I was wondering if you can recommend any software to generare this domain given a pebble diameter and the dimensions of the vessel. It's important to be able to differenciate between the solid and the gas for some analysis. For example, besides doing the flow simulations I would like to determine the solid fraction inside an arbitrary parcel of the domain.

I would appreciate any recommendations regarding how to process this kind of data since I've never worked with such domain.

Thanks in advance!

Hey! I'm working on some simulations with fluent and I was wondering if anyone know how to get the (field) values of each term on a conservation equation being solved, specifically on the energy eqn. This is to analyze which terms dominate on different regions of the domain by comparing for example the convective term with the conduction/diffusion term.

Thanks in advance!

Hi,

I’m working on a simulation in Ansys Fluent where I need to apply a parabolic velocity profile at the inlet of a concentric annular pipe. However, I want this profile to start from a certain distance downstream, not right at the origin.

Pipe Geometry: Concentric annulus with an inner diameter of 10 mm and an outer diameter of 15 mm.

Velocity Profile: A turbulent profile should vary across the radius and start only after a specified offset along the pipe’s axis (e.g., 100 mm from the origin).

Current Issue: I can get the profile to work if the pipe starts from the origin, but when I try to apply an offset, I can’t get Fluent to recognize it correctly.

When the pipe starts from the origin, I usually use the named expressions as

radius = sqrt(y**2+z**2)

Radius = <value> [m]

Umax = <value> [m/s]

U = Umax*(1-(radius/Radius)^2)

If someone is familiar with how to give expression for this, please comment. Thanks in advance.

https://preview.redd.it/nivfp4u4xxxd1.png?width=548&format=png&auto=webp&s=fe9dae90d2b47ff7e87bee4f272c8472b5033648

I am running the fluentbench.pl script to benchmark a large model on various machines. I am using this command:

/shared_data/apps/ansys_inc/v242/fluent/bin/fluentbench.pl -path=/shared_data/apps/ansys_inc/v242/fluent/ -noloadchk -norm -nosyslog Roller_Zone_M -t48

Some machines only have 28 cpus, so I replace 48 with that number. On those machines the load via "top" never exceeds 28. But on the 48 cpu machine, it stays at 60. The job runs very slowly compared to the 28 machines ( which actually has older and slower cpus )!

The cpu usage of each core seems to fluctuate between 50-150%. Here are the cpu specs:

[me@dell48 ~]$ lscpu
Architecture:        x86_64
CPU op-mode(s):      32-bit, 64-bit
Byte Order:          Little Endian
CPU(s):              48
On-line CPU(s) list: 0-47
Thread(s) per core:  1
Core(s) per socket:  24
Socket(s):           2
NUMA node(s):        2
Vendor ID:           GenuineIntel
CPU family:          6
Model:               85
Model name:          Intel(R) Xeon(R) Gold 6248R CPU @ 3.00GHz
Stepping:            7
CPU MHz:             3583.197
CPU max MHz:         4000.0000
CPU min MHz:         1200.0000
BogoMIPS:            6000.00
Virtualization:      VT-x
L1d cache:           32K
L1i cache:           32K
L2 cache:            1024K
L3 cache:            36608K
NUMA node0 CPU(s):   0-23
NUMA node1 CPU(s):   24-47

I gradually start to understand the SUPG term, but my understanding is still a mess, and it seems that the shock capturing utilize the projection on the residual, is there any systematic review on these two topics for compressible flow?

Hey everyone,

I’ve been trying to understand AMReX since August, but I haven’t made much progress. My project presentation is in two weeks, and I’m feeling stressed.

I’ve searched the internet, but I can’t find clear info on how to develop a solver or use the functionalities that AMReX provides.

I’d be really grateful if someone could teach me or guide me through the process.

Thanks!

residuals (mid-run)

I'm working on a personal project involving wind around/through buildings; and this is the first time I've come across a residual with these little spikes that get resolved almost immediately. I just wanted to ask if there's anything I can be learning from it, or if there's something I need to do to avoid it. My background is in geoscience; I'm sure my data is nonsense from an engineer's perspective and I'm fine with that at the moment.

This particular run is DES; k-w SST for incompressible flow. I'm honestly prioritizing cool looking results over accuracy, so for now I'm just running lots of different models through the same mesh to get an idea of what different outcomes look like. Any setup suggestions are welcome. At the moment I'm using FreeCAD for geometry and a free OpenFOAM GUI for meshing and sims.

Hey everyone!

I'm looking for open-source or free software to calculate friction losses in pipelines, ideally something that’s user-friendly for setting up complex layouts. Key features I need are:

• Accurate friction loss calculations that account for elevation changes, bends/elbows, and variations in pipe diameter.
• 3D visualization of the pipeline layout would be a bonus, as it helps with verification.
• Ideally, intuitive input options (e.g., a table-based or graphical interface) to simplify setting up the pipeline structure and fluid properties.

I've looked into options like OpenFOAM, but I’m wondering if there are other tools that might be less technical and quicker to set up while still being precise enough for engineering calculations.

Thanks in advance for any suggestions!

I woul like to know ho much does a cfd would be better than xflr5 to stimate the performance of a 3D wing in a turbolent flow (Re~10^6 ). In other words how inefficient is xflr5?