[CFD] Pseudo-Transients for Steady State CFD (Part 2) - Length and Velocity Scales

  Рет қаралды 6,739

Fluid Mechanics 101

Fluid Mechanics 101

Күн бұрын

An introduction to pseudo transients and how they can be used to calculate steady-state solutions in CFD (Part 2). Timestamps:
0:00 Introduction
1:00 Recap
3:28 Length Scale Calculation
12:10 Conservative vs Aggressive
14:26 Solids Velocity Scale
19:21 Internal Energy
24:05 Propagation Speed
25:16 Thermal Diffusivity
30:16 Volume Averaging
33:31 Units
34:31 Summary
37:02 Outro
#pseudoTransient #fluidmechanics101 #cfd
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Some useful references
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1. Ferziger & Peric, 'Computational Methods for Fluid Dynamics', 3rd Edition, Springer-Verlag, Berlin, Heidelberg, New York, 2002.
www.amazon.co.uk/Computationa... [Page 118, 149]
2. ANSYS CFX Solver Theory Guide
Chapter 1: Basic Solver Capability Theory
Section 1.10: Automatic Timescale calculation
============================================
Want to learn more?
============================================
Grab a copy of my CFD Fundamentals Course (for beginners):
www.udemy.com/course/computat...
Learn how to write your own CFD code in MATLAB and python (for intermediates):
dr-aidan-wimshurst-s-school.t...
Learn how I draw my figures and diagrams in Inkscape (for everyone):
dr-aidan-wimshurst-s-school.t...
============================================
Did you like the video?
============================================
Download the lecture slides from my website:
www.fluidmechanics101.com/pag...
Buy me a coffee to say thanks:
www.buymeacoffee.com/NKEZrhvg0
Support the channel on Patreon (and get useful extras for your CFD studies):
/ fluidmechanics101
============================================
Donations:
============================================
1) PayPal
www.paypal.me/fluidmechanics101
==================================
Disclaimer
==================================
The methods, algorithms, equations, formulae, diagrams and explanations in this talk are for educational and demonstrative purposes only. They should never be used to analyse, design, accredit or validate real scientific / engineering / mathematical structures and flow systems. For such applications, appropriate trained, qualified and accredited (SQEP) engineers / scientists should be consulted along with the appropriate documentation, procedures and engineering standards. Furthermore, the information contained within this talk has not been verified, peer reviewed or checked in any way and is likely to contain several errors. It is therefore not appropriate to use this talk itself (or any of the algorithms, equations, formulae, diagrams and explanations contained within this talk) as an academic or technical reference. The reader should consult the original references and follow the verification and validation processes adopted by your company / institution when carrying out engineering calculations and analyses. Fluid Mechanics 101 and Dr. Aidan Wimshurst are not accountable or liable in any form for the use or misuse of the information contained in this talk beyond the specific educational and demonstrative purposes for which it was intended.

Пікірлер: 25
@jessbuildstech
@jessbuildstech Жыл бұрын
Fantastic video, I was really excited for part 2 to drop! 🎉
@user-kj3pj5oi8i
@user-kj3pj5oi8i Жыл бұрын
your talk is very helpful! Thank you
@AeroconX
@AeroconX Жыл бұрын
Great content! Thank you
@BUGOCENTER
@BUGOCENTER Жыл бұрын
I love your contents, but can you explain about acoustics model? And How's relation between acoustic model and viscous model? It's very interesting to watch and listen, big thanks.
@ting-juwei6584
@ting-juwei6584 Жыл бұрын
Fantastic video, could you talk about the cavitation model in CFD~ Thanks in advance!
@fluidmechanics101
@fluidmechanics101 Жыл бұрын
Cavitation modeling is quite tricky. Do you actually need to model the bubbles, or do you just want to predict whether cavitation is likely? If you only care about whether cavitation is likely, you could just look at pressure contours and see where the pressure drops below the vapour pressure?
@CFDIntech
@CFDIntech Жыл бұрын
​@@fluidmechanics101 I think that both approaches will be very interesting to see, thanks!
@EngLhag
@EngLhag Жыл бұрын
Around 11:00 and 13:40 : Shouldn't the formula be a simple cube root of the volume (with a 3, not 1/3, there)?
@fluidmechanics101
@fluidmechanics101 Жыл бұрын
Ah yea, it's meant to be cube root, so either use a 3 there or just go with V^1/3
@gopinathnk
@gopinathnk Жыл бұрын
If the solid domain is made of multi-layered material with varying thicknesses, do we select the one with min (delta t) or still consider the entire domain as one and use volume-averaged properties?
@fluidmechanics101
@fluidmechanics101 Жыл бұрын
Good question. If the perturbation travels through the thickness of the material (through the layers, one by one) then you could happily use the volume average. However if the perturbation travels along the length, then take the minimum. So you will need to make a judgement. I would guess that it is mostly through the thickness, so you can use volume average
@mohammaderfankarami1744
@mohammaderfankarami1744 Жыл бұрын
Hi there. thanks for your useful videos. Can I have one demand? Could you please create video about sparse matrix and the way which modern cfd codes use that to store the matrix elements and solve the problem?
@fluidmechanics101
@fluidmechanics101 Жыл бұрын
Good suggestion. I will add it to my list 😊
@mohammaderfankarami1744
@mohammaderfankarami1744 Жыл бұрын
@@fluidmechanics101 Thank you so much.
@cwong9241
@cwong9241 Жыл бұрын
Is it possible to lower the URF and use small pseudo time step factor to stabilise the calculation. Does it mean it will take forever to get a converged simulation? Many thanks
@fluidmechanics101
@fluidmechanics101 Жыл бұрын
Yea, smaller URF or pseudo time step will just take more iterations to reach a solution. Hopefully it won't take forever! Usually if you are needing more than 5000 iterations, then something might be up with your calculation
@cwong9241
@cwong9241 Жыл бұрын
@@fluidmechanics101 thank you for your reply. The best channel for cfd!
@user-oy3dk5jd5e
@user-oy3dk5jd5e Жыл бұрын
Dear sir. Spatial discretisation schemes for the convective fluxes like Roe scheme. And AUSM scheme using only in. The inviscid flow (Euler equations) or used for the compressible RANS equations . Answer me please and sorry for wasting your time 🥺
@SaurabhKumar-lg8gv
@SaurabhKumar-lg8gv Жыл бұрын
u have a discord grp could you share its link if it's not member's only
@fluidmechanics101
@fluidmechanics101 Жыл бұрын
discord.gg/uGkUnWac9S
@anirbandas4201
@anirbandas4201 Жыл бұрын
The link for discord grp you shared is not working.
@fluidmechanics101
@fluidmechanics101 Жыл бұрын
Yea, the link keeps expiring, even when I set it to 'never expire' 😑 try this one: discord.gg/uGkUnWac9S
@anirbandas4201
@anirbandas4201 Жыл бұрын
@@fluidmechanics101 This too not working.
@fluidmechanics101
@fluidmechanics101 Жыл бұрын
Strange. Try this: discord.gg/Cn37N3Qg
@anirbandas4201
@anirbandas4201 Жыл бұрын
@@fluidmechanics101 Thnks this link worked.
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