What is Cfd: Definition and 129 Discussions

Computational fluid dynamics (CFD) are used to understand complex thermal flow regimes in power plants. The thermal power plant may be divided into different subsectors and the CFD analysis applied to critical equipment/components - mainly different types of heat exchangers - which are of crucial significance for efficient and trouble free long-term operation of the plant.

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  1. S

    Improve Result of my CFD results

    Im running a CFD simulation. Looking at improve my CFD simulation. my mesh is currently low density. Q) Would increasing mesh density around the boundaries of the air craft wing capture the forces (velcoty & pressure) on my velocity map and added streamlines.
  2. S

    Engineering Solve Inaccurate CFD Predictions: Improve Results

    Hi Im confused with what the CFD Results show or mean. I have never done CFD before and don’t have any material explaining it. Question Find areas of potential inaccurate predictions in the simulation and improvments. This is the instructions I had to follow...
  3. prithika

    I Effect of vent ratio on the drag coefficient of round parachutes

    For my 12th grade school project, I'm planning to research on the effect of vent ratio on the drag coefficient of round parachutes. My idea was to make small model parachutes and drop them from a height, and derive the drag coefficient after certain assumptions. But I also thought it'd be...
  4. B

    I Flow rate calculation of coating application

    Dear all, I'm currently working on a basic coating application and I'm struggling to get the flow rate stable. I'm trying to figure out how to calculate the theoretical flow rate in the application. The coating is stored in a pressure tank, which we put on an overpressure of 15psi. From the...
  5. casualguitar

    Modelling of two phase flow in packed bed (continued)

    Previous post linked here, where a model for the two phase flow of air through a packed bed was developed: https://www.physicsforums.com/threads/modelling-of-two-phase-flow-in-packed-bed-using-conservation-equations.1008754/ The first few comments on this new thread will be copies of the...
  6. JD_PM

    Understanding the source code for an OpenFOAM solver (CFD)

    I am trying to understand the following code (it starts from line 59) and there are pieces I do not understand. argList::addNote ( "Solver for two incompressible, isothermal immiscible fluids with" " phase-change.\n" "Uses VOF (volume of fluid) phase-fraction based...
  7. casualguitar

    Modelling of two phase flow in packed bed using conservation equations

    Previously, I have seen the derivation of the energy conservation equations for simulation of single phase flow in a porous media (a packed bed). These are the energy equations for the solid and fluid respectively: I understand the derivation, however, these equations will only work when the...
  8. M

    (CFD) Problem with C code for 1D linear convection equation

    This is my c program below. Again everything works as expected up until the highlighted lines or the second for loop. When i run my program to output the arrays contents i get bizarre numbers that are not correct. # include <math.h> # include <stdlib.h> # include <stdio.h> # include <time.h>int...
  9. J

    Typical surface roughness heights for aircraft surfaces

    Hello! I am investigating some preliminary aerodynamics on a regional turboprop and for the drag model the surface roughness height of the airplane is required as an input. For this i do not have any data. In which range are the typical values for modern aircraft surfaces? Thanks a lot!
  10. K

    Calculating torque from moment results in CFD analysis

    Hi there, attached were the results: https://prnt.sc/v3yg1f Both are negative and need to be added together to get the torque force. Calculations are from a model of specified radius and input air speed, its a turbine. Just need help in understanding what the negative results mean and how they...
  11. M

    Running CFD with python and bash: not in agreement

    Hi PF! I'm running a CFD (computational fluid dynamics) program OpenFOAM. Liquid is sucked from a tank, where the velocity at the tank outlet (suction point) is controlled by a python script. The boundary condition for velocity at the outlet is below, line 4 being the velocity prescribed at...
  12. M

    Gmsh (meshing for cfd programs) keeps crashing

    Hi PF! Hello all I just downloaded gmsh on Linux 64 bit running Ubuntu 18.04. When I attempt to open a .stp file I created in salome, the program crashes, leaving a terminal output "segmentation fault (core dumped)". Any idea what is going on? The step file is...
  13. M

    What computer setup for CFD simulations 1000$-2000$ budget?

    I'm running computational fluid dynamic simulations and am looking into building a desktop. But there are so many options. At this budget, what would you buy? Is it better to buy used CPUs, etc?
  14. M

    Fluids CFD and OpenFOAM

    Hi PF! Does anyone know how to pin the fluid-solid contact line in OpenFOAM? There has to be a way to do this, and I've tried the cfd-online community but they're largely inactive and consequently no one has replied to my question. Any help or guidance is greatly appreciated!
  15. M

    C/C++ Running a C++ code from oomph-lib (a CFD software)

    Hi PF! I recently installed the computational fluid dynamics software oomph-lib, which is similar to OpenFOAM. After installing, I'm trying to run a tutorial provided with the program, described here. I think all I need to do it run the .cc file here, so I type into the terminal >> gcc...
  16. T

    Counterfactual Definiteness and MWI in Wiki

    Summary: Counterfactual Definitiveness and Many World's Interpretation Sorry for all these threads, my noetic fluids and bursting. Wiki states the following: In quantum mechanics, counterfactual definiteness (CFD) is the ability to speak "meaningfully" of the definiteness of the results of...
  17. M

    Install oomph-lib, a CFD opensource software

    Hi PF! I'm trying to follow these instructions to install an open-source CFD software on Ubuntu: http://oomph-lib.maths.man.ac.uk/doc/the_distribution/html/index.html#download After downloading the tar file http://oomph-lib.maths.man.ac.uk/tar_file_directory/, I type the command >> tar xvfz...
  18. Anachronist

    Ridiculously low drag coefficient from OpenFOAM CFD

    (New thread following up to a conversation in another thread). I'm using SimFlow 3.1 with OpenFOAM 5 on Linux to try to evaluate the drag coefficient of a water rocket body, constructed from a 2-liter Coke bottle with a conical nose, traveling through air at 77 m/s. This should be a simple...
  19. Navier-Stokes Equations - Numberphile

    Navier-Stokes Equations - Numberphile

    Tom Crawford (sporting a Navier-Stokes tattoo) talks about the famed equations - subject of a $1m Millennium Prize.
  20. M

    Fluid Oscillating in a Channel CFD

    Hi PF! I'm simulating two fluids, air (blue) and water (red), in a 2D rectangular channel. See picture below: I've turned gravity and viscosity off, and have ##\rho_w=1000## kg/m^3 and ##\rho_a = 0.01## since it cannot be zero. I've also enforced a static contact angle of ##\theta = 71^\circ##...
  21. T

    Speed usage in Lattice Boltzmann Method

    One thing that confuses me is the physical speed and sound speed. The lattice sound speed cs=1/sqrt{3} corresponds to the physical sound speed for isothermal flow (sqt{RT}). Why isn't the physical speed (e.g. inlet speed up of lid cavity) converted and use accoringly? $$c_p=\sqrt{RT}≈330m/s...
  22. Jeviah

    CFD analysis of a turbine, interpreting torque values

    Hello, I am using CFD to analyse a Kaplan turbine and am unsure on how to interpret the torque values as they come as x, y and z components. My understanding is that the z component in this case will determine the rotation direction depending on whether it is positive or negative however I am...
  23. M

    Difference between system subchannel and CFD codes

    Hi everyone, I am researching how numerical simulations have evolved over the years in nuclear reactors for assessing the thermal hydraulics inside the reactor core. I have found vague information in regards to the three different main numerical techniques but want to learn more. So far...
  24. L

    Other Asking for recommendation on Fluid Dynamics and CFD textbooks

    Dear All I am an undergraduate student studying in physics. I would probably get into research that needed fluid dynamics and CFD (computational fluid dynamics) skills. Previously I have not been taking a formal fluid dynamics course since there is none. I would like to pick up those skills by...
  25. A

    Calculating the velocity and pressure profiles across an axial fan

    Hi, This is my first post on the PhysicsFormus I am trying to design an inlet and outlet for an axial fan and calculate velocity and pressure profiles in the duct. See the sketch attached. The ultimate goal is to carry out a CFD study but I was wondering if there is an analytical solution for...
  26. M

    MATLAB Switched from win10 and MATLAB to ubuntu and python"q"

    Hi, I felt like I have to learn more than one coding language, and wanted to strengthen my coding skills in general. I am good with Relap5 but I want to learn OpenFoam. is what I did logical and going to be worth the pain ? also I only have the Relap5 version of a windows ,is it possible to run...
  27. D

    Beginner's approach to CFD software?

    I am currently an "intern" at a company for a position primarily involving drafting cell site equipment. That is going quite well. But the owner of the company (an old friend of mine) has asked me to look up computational fluid dynamics softwares and begin to tinker with one, because he is...
  28. R

    MATLAB Finite element skeleton code for matlab

    Hello, Does anyone know if a finite element skeleton source code exists. Finite element can be used for structural memebers, gas dynamics, etc. But the over all stepping software is the same and then just input the core equations. My application is for pseudo one dimensional compressible...
  29. S

    Modeling of two-phase flows in electric and magnetic fields

    Hi, Can anyone direct me to some literature that describes the numerical solution of full Maxwell's equations and Navier-Stokes equations for two-phase/multi-phase flows in coupled electric and magnetic fields. Thanks!
  30. berkeman

    Looking for CFD simulation help on this Aero experiment

    Hoping to get some help on a stability analysis of this setup...
  31. M

    Couple Thermal-Hydraulics & Kinetics for PWR LOCA Study

    Is it possible to couple a thermal hydraulics code with a kinetics one ? , main purpose is to study the behaviour of kinetics due to a LOCA or any other changes regarding the coolant/moderator flow " talking about a PWR " .
  32. entropy1

    I What is the difference between cfd and realism?

    What is the difference between counterfactual definiteness on one side and realism on the other? And what are their definitions? (references will be welcome if given).
  33. N

    Flow Over a Rotating Bridge CFD

    Hi everyone, This is my first post as I am a new member here. I am trying to simulate an opening of a bascule bridge and study the flow over it in Fluent. I simplified the problem by allowing the bridge to be represented by a flat plate and I used Reynold's Number scaling to scale my dimension...
  34. F

    CFD Modeling of Flue Gas Pollution Dispersion

    I've previously studied and used the k-epsilon turbulence model within Ansys to model water in a small stirred vessel. I am now interested in CFD models appropriate for modeling flue gas dispersion. I'd like to know: What additional considerations are required for modeling a gas as opposed to...
  35. F

    CFD Fluent airflow simulation -- "Error: no periodic zones adjacent to grid interface"

    I have created a savonius turbine model with 2 blades using 3D gambit. I want to simulate the flow of air flowing so as to drive the turbine savonius spin (unsteady, incompressible). Geometry consists of 3 volume boxes (domain tunnel flow), cylinder (domain grid interface), blade savonius...
  36. J

    Inviscid flows and the turbulent (eddy) viscosity

    Hello, After Favre averaging the momentum equation for an inviscid flow, the following can be obtained: $$\frac{\partial}{\partial t} \left(\overline{\rho}\tilde{u}_i \right) + \frac{\partial}{\partial x_j}\left( \overline{\rho}\tilde{u}_i \tilde{u}_j \right) + \frac{\partial...
  37. ramzerimar

    Courses Is CFD fluid mechanics + computer science?

    I'm having fluid dynamics classes right now and I'm enjoying it very much (much more than my solid mechanics classes, by the way). Also, I do like programming and computer science, and CFD looks like a very interesting field. I'm developing a real interest for it. One question for those who are...
  38. Eye_in_the_Sky

    I State Separability & CFD

    I am thinking of the usual "Alice and Bob" type scenario. If I choose to view the measuring instruments of Alice and Bob as "classical objects in spacetime", am I not then forced to say the following as well? 1) The joint-state of the measuring instruments is separable throughout the whole of...
  39. EternalSeekerX

    I Are CFD codes like OpenFOAM used in other realms of physics?

    Hey guys and gals, In my 4th year I got interested in cfd while doing a flat plate case. Fast forward to after grad and while I am looking for a job(Still looking :( ) I have been playing with Linux and open foam. I looked into astrophysics and plasma physics and such as they interest me to. So...
  40. ramzerimar

    Engineering Opening a CFD consulting firm?

    I've been thinking about entrepreneurship in the engineering field. Unlike other fields like computer science, where small companies with small investments often end up becoming huge business, engineering is usually a very expensive thing. So consulting is a way for those who don't want to work...
  41. M

    AutoCAD inventor as CFD software

    Can Autocad inventor be used as a cfd software such as ansys fluent? Thank you.
  42. R

    CFD turbulent fluid, discussion about pressure gradient

    I simulated an incompressible turbulent flow across a tube. I managed to solve it using OpenFoam and the results seem to be right. However, I noted some vacuum pressure after the sudden expansion but can't figure out why the pressure decreases and then increases again. According to Bernoulli's...
  43. M

    A How to Solve Isothermal Incompressible Navier-Stokes for Compressible Fluid?

    I did a lot of googling but could not find a satisfying answer to my question, hence a post here. Question: How to solve (or close) the isothermal incompressible Navier-Stokes equations for an isothermal compressible fluid? Situation: We have a compressible fluid, for example a gas. The flow...
  44. morrobay

    B Distinguish Contextual ,Non Local,Non Realistic (Non CFD)

    Case One : In Bell test violations can outcomes be they (1) contextual outcomes ( not pre - encoded in measured object but arise in interaction with object and measurement apparatus) be distinguished from (2) non realism /non counter factual. And (3) from non local effects in a space like...
  45. R

    A FEM for Solving PDEs: Beginner Textbooks & Fluid Flow

    Hi, my background is in mathematics, and theoretical physics. I am new to the realm of solving PDEs using Finite element methods, does anyone know of any good introductory level textbooks for course notes? I had a poke around online and couldn't find anything overly useful. Also I am...
  46. G

    Guidance or tutorial of applying pseudo-material method

    Hi, I'm working on a project of coupled simulation involving MCNP and Fluent, and having trouble with how to apply the pseudo-material method in cross section handling. Is there any related material or tutorial? Or, does anyone know the procedure of applying the method and what kind of files the...
  47. B

    CFD of pressure reducing regulator - Please help

    I'm looking for an example of CFD analysis on a pressure reducing regulator. I think may be fairly complicated because the main valve position is not fixed but rather controlled by the pressure differential acting across the valve, the main valve spring, and the load spring minus the pressure...
  48. Eye_in_the_Sky

    I CFD - Counterfactual Definiteness

    I am thinking about a single run in a typical Bell-type scenario: A joint-measurement of an (appropriately prepared) entangled property is performed in spacetime regions A and B at spacelike separation. Regarding the above, in conjunction with Quantum Theory, would you say the following...
  49. B

    B Exploring Counterfactual Definiteness in Bohmian Mechanics and Its Variants

    In standard Bohmian Mechanics, does the pilot wave support counterfactual definiteness? How about other variants of BM, don't they? Can you mention or bring up a site that summarize all variants of BH and whether the pilot wave in each support counterfactual definiteness. Thank you.
  50. nn2e11

    Python Doublet + Uniform Flow // Streamfunction Polar Plot Help

    Hello, Python,CFD and PF newbie here. I am using Spyder (Python 3.5) and I managed to plot my streamfunction in cartesian coordinates. I tried transforming and plotting in polar coordinates but I am not sure that what i have done is correct. I am not even sure what the plot should look like :/...