CFD Online

Computational Fluid Dynamics

[link]

engineering

engineering is a forum for engineering professionals to share information, knowledge, experience related to the principles & practices of the numerous engineering disciplines. engineering is **NOT** for students to ask for guidance on selecting their major, or for homework / project help. Read the sidebar BEFORE posting.
[link]

Formula 1

The best independent Formula 1 community anywhere. News, stories and discussion from and about the world of Formula 1.
[link]

CFD simulation of Beirut explosion...

CFD simulation of Beirut explosion... submitted by Pyrojodge to shockwaveporn [link] [comments]

An experimentally validated CFD model of a supply air window

An experimentally validated CFD model of a supply air window submitted by kuftikufti to EngineeringPorn [link] [comments]

I'm trying to design an intake for a fan but I don't have any CFD software. Do you think the air will make it around this curve?

submitted by skyersjet to AerospaceEngineering [link] [comments]

Do you think bringing CFD post-processing into VR is a cool idea?

Some of the major benefits of bringing CFD post-processing in VR are
1) You can feel the liveliness of the objects in front of you in VR.
2) The problem area and its location in the simulation will be explicitly clear to you in VR.
3) You can import simulation results from all major software
4) It can be used with normal desktop/laptop with affordable mobile VR headset (and of course with High-End VR headset)
It's just based on my experience with CFD users. But I want to see what other experts in the CFD domain think.
What is your opinion about this?
submitted by visulity to CFD [link] [comments]

Plain english warning about CFD trading, just something I wish someone had told me

tl;dr - trading CFD's is the equivalent of drag racing your drunk mate down the freeway into oncoming traffic. No self respecting adult would bother with them, CFD's are for cocaine-snorting thrill-seeking morons (like me apparently) who have no respect for risk management. Don't gamble with your savings.

What are CFDs
CFD's are 'Contracts for Difference'. Very simply, if you have a trading account with the right permissions you can trade in CFD's.
Why are they dangerous
Because say you trade $250, on a normal trade (ie stocks etc) if the price falls by 10% you lose $25, which sucks but isn't world ending. CFD's are NOT like that - they are 'leveraged' which just means that if you put up $50 your exposure is many many many many times larger than that
EXAMPLE
You buy 50 contracts on a stock that is trading at $100 a share.The stock then drops $10 in value.Your exposure is (50 * 100) = $5,000 BUT because your 'margin' is only 5% of that, the initial amount you put up is a mere $250.
So to illustrate:
Stock Trading
Initial Investment - $250
Value drop - 10%
Loss - $25
CFD Trading
Initial investment - $250
Value drop - 10%
Loss - $5,000

Closing remarks
These things are illegal in the US for a good reason.
CFD's are for suckers, don't listen to anything that you hear to the contrary. EU regulators say that 76% of CFD accounts lose money. Let me say that again, 76% of these things lose $&*#ing money. If the odds at the casino were 1:4 there is no fkn way anybody would go. When you trade CFD's you are essentially just gambling but with WAY WAY worse odds.Cited: https://www.iexpats.com/76-of-cfd-traders-lose-money-on-their-deals/
You can't make long investments with CFD's, they aren't a long-term strategy and they are not part of ANY investment strategy with a reasonable risk profile. Please don't make the mistake I did and get sucked into trading them, it's stressful as hell and it is pure bravado driven bullshit.

Stay safe out there folks, times are nuts
Edit 1: Formatting got stuffed up
submitted by loathingq to AusFinance [link] [comments]

Airflow in Winter One -- A Long Discussion About CFD-Optimized SFFPC case design

A pretty cover image to entice you to read this wall of text

Background & Context

A year ago, I set out to design an airflow optimized Small Form Factor PC case. You can read up about the design iterations in this SFF.net thread, if you want more context

I. Introduction:

Hi everyone! 🙂
In this post, I will be giving you a detailed look at what CFD has allowed me to achieve with Winter One. Until now, I've been showing you CFD images, but hadn't really talked about what I was attempting to do. Now I'm ready to reveal what Airflow looks like in the Production Version of Winter One. Buckle in, though, it's going to be a long read :)

II. This is cool, but Why Bother?

The promise of Small Form Factor systems has always been “you can cram desktop components into a small space, and it’s a better experience than those large, space-inefficient towers”
But the biggest drawback to SFF systems are usually thermals or noise. Most SFF cases handle mid tier components just fine, but most people will struggle to cool high end components crammed into a sub-10L chassis. The truth is there are few cases that can adequately cool top tier parts, like an OC’d 9900K + OC’d 2080Ti. And even the ones that can adequately cool these parts struggle to do so while remaining quiet.
At the end of the day, you cannot cheat physics… High end components in a Tiny Box = lots of heat. The only way to remove that heat? Airflow. And yes, this applies even if you liquid cool. Radiators are only as effective as the amount of air you can push through them to pull heat from the coolant.

III. What does Good Airflow in an SFFPC case look like?

Here are some results from the final airflow simulations for Winter One. There are 4 configurations. For a detailed explanation of why/how airflow was optimized in this case, please read Section IV.

IV. Airflow Enhancements in Winter One

1. Reducing Flow Restriction across panels

The Hole Size in all the panels for Winter One was chosen based on simulations that looked at ∆P across the plate, and edge perimeter vs Circle Area, while also balancing Percent Open Area.
Smaller holes are inherently more restrictive, even if you have a lot of them, compared to larger holes… this is because the flow of particles at any boundary becomes stagnant, and creates drag for nearby particles. So, the greater your Perimeter / Area ratio, the more flow restriction there will be.
The lower the ∆P across the plate, the easier it is for air to cross from one side of the plate to the other, preventing stoppage of flow. This is especially important when it comes to passive cooling, where natural convection is very sensitive to flow restriction, which can trap the heat within the case.

2. Foot Height — ensuring the case can breathe

With a hole diameter chosen, I had to make sure that when Winter One was placed on a surface, The case was able to intake or exhaust air satisfactorily. Far too many small form factor cases use the smallest possible feet to avoid adding volume. However, this drastically harms cooling, whether the case is set up for intake or exhaust at the bottom. Winter One's volume is 14.4L without protrusions, and 15.4L with protrusions.
I found that a foot-height of 2cm ensured excellent airflow into / out of the case. This number is dependent on the hole geometry of your panels, as well as some other factors that are discussed in #6. For more restrictive panels, this value can be smaller, as your panel is restricting flow more than the availability of air through the gap created by your case feet.

3. Linear Airflow Path / minimizing 90º Turns

For every 90º Turn made by flowing air, you lose about ⅓ of the pressure (and therefore, velocity). So, if there is a 90º turn being made, it’s important to make sure that it’s happening for very good reasons… In the case of Winter One, the only recommended airflow configuration where 90º turns occur is the all-exhaust configuration that allows each radiator to receive cool, ambient air.
In all other airflow configurations, a linear path is preserved. Whether solid or perforated side panels are used, the bottom >> top airflow is maintained. Perforated Side Panels are useful for passive cooling, and for all-exhaust setups, but also help cool tall components, especially those pressed up against the panel itself. Therefore, it is recommended with Triple Slot GPUs or CPU air coolers above 55mm.

4. Turbulent vs laminar flow, and Optimizing for Human Perception of Acoustics.

The transition from laminar to turbulent flow can create a single acoustically distinct whine. This has a significant effect on the perceived acoustics of the case. I tuned End Plate thickness, and distance from the fan blades, in order to create 2 smaller transitions to turbulent flow, before air is accelerated by the fans. This spreads one acoustic peak into 3 separate peaks, creating a more pleasant noise profile.

5. Eliminating Internal Surfaces, and Boundary Layer Drag.

Removing the central spine in Winter One led to a 25% increase in airflow velocity throughout the case regardless of airflow configuration.
We also took great care in creating the frameless design of Winter One. In addition to opening up more internal volume for building in, the elimination of protrusions allows air to flow cleanly through the enclosure.
Together, these efforts eliminated almost all regions of stagnant air behind the GPU, motherboard, and power supply.

6. Backflow Barriers on the End-plates.

When fan speeds are pushed higher, we found that air had a tendency to loop around, and enter from the edge of the end plates. To address this, the geometry of the inside of the end plate was altered, and the fan / radiator plate was widened in order to provide a physical barrier to limit the backflow of air. At the same time, this does not narrow the intake or exhaust "cones" of each fan, which would negatively impact flow rates.

7. Utilizing Exterior Eddies to Separate intake and outlet Flow.

Notice the swirling currents near the top and bottom corners of the case in the all-exhaust configuration? This is not an accident. The feet height and the size, distance, and even spacing of the holes on the side panel, the top and bottom plates, and more, were ALL carefully controlled to purposely create large eddies outside the case.
Why go through the effort? Eddies are circular regions of “locally” stagnant airflow. If we design our case to precisely place them where they need to go, these eddies separate the intake and exhaust flows, preventing recirculation of air in the case!!! This is one of the secrets to Winter One's ability to cool so well.
These are present in every supported airflow configuration in Winter One (scroll up, and you'll see them!). Getting this to work with the variety of ways one can set airflow in Winter One was incredibly difficult. They are formed anywhere an intake and exhaust come too close to one another, and we’d normally see recirculating flow.
This was the single most difficult airflow problem to solve for Winter one. It took about 1500 hours of engineering and simulations. Around 25GB of CFD data sitting on my computer (more than half of ALL the CFD data!!!) is related to this problem alone.

8. Why All-Intake is BAD for SFFPCs.

This brings us to the 4th CFD image. This is the “All Intake” configuration, tested for Winter One. This is NOT a recommended or supported cooling configuration, and calls into question the common wisdom of operating SFFPC cases strictly with intakes. (obviously exceptions exist). This is a good time to point out that practices seen in the ATX world do not always translate to Small Form Factor PCs. All-Intake airflow configurations are one example.
In small form factor cases, fan intake and exhaust flows are often too close to one another to run all-intake airflow configurations. The issue is that the highest airflow velocity is at the intake, and the lowest airflow velocity exists at the exhaust. If this exhaust comes too close to an intake, there is a significant risk of re-circulation.
The All-Intake flow data is included so we can see what happens -- OVER 60% of the warm air leaving Winter One is too slow to escape the intake of the fans, and is sucked back in!!! In this simulation, the fans are only operating at 1000 rpm. This problem worsens as fan speed increases. Furthermore, the “bad” (unintentional) kind of eddies are formed within the case, trapping hot air inside the system. Both of these issues lead me to suggest that no one should use an all-intake airflow configurations in Winter One.
If you’d like to keep some positive pressure in the case to combat dust, consider running the intake fans at about +150 rpm, compared to the exhaust fans. This has the effect of creating higher pressure within the case, while also maintaining a high exhaust velocity, and the barriers mentioned above.

V. How was CFD performed?

This is FlowSim so it uses a k-e model, with a Lam-Bremhorst extension -- a modification that adds support for laminar and transition flows to the "traditional" turbulent-only k-e by using a transport equation for dissipation rate. It relies on wall-distance to pull this off, however. This allowed me to support laminar, transition, and turbulent flows, while still being computationally reasonable.
Meshing had to be done manually, and was quite fine. Layers of meshing starting from 1 mm to 2 mm, then 4 mm, and then 8mm in concentric shells, and then adjusted to be more relaxed, gradually as you move away from the case or fans. For curved surfaces, 0.01 radian changes are a new mesh... The case is simulated in a full size room, to eliminate issues with the boundaries messing with flow, but the meshing is relaxed further as you move away from the table the case sits on.
I needed to optimize this... because running the entire room at 1mm mesh would take 3 weeks on an 8 core CPU... After optimizing, and getting around 12M cells, the runs take around 30 hours each, and results are sane, with great detail in flow around the case, and very coarse laminar room flow.
These are 3D simulations (Solidworks supports both 3D and 2D, and even a hybrid method with Symmetry). Of the 12M cells used for each model, about 3M are in direct contact with the solid parts of the case. The finest meshing is about 1mm cells. and another 6M are around or within the case volume, ranging from 2mm to 1.6cm in size, based on where they are, with more relaxed detail the further they get from any solid... the last few million cells are diffusely spread through the room. This is just to keep any weird edge effects away from the case itself.
The simulation becomes drastically less accurate the further away you are from the table surface and case itself... since the L-B extension relies on wall-distance, and flow in the rest of the "room" is well in the laminar region (15cm/s or below), and the L-B function isn't as reliable in regions so physically distant from the walls / surfaces in the "room", the k-e function's weaknesses begin to show...
However, within and around the case, it's quite accurate, computationally cheap (only 30 hours for a single simulation on an 8-core CPU isn't half bad), and affordable to use without resorting to renting / spinning up a small compute cluster. Only downside, it eats up RAM at a pace that would make Google Chrome blush...

VI. Concluding statements

When I set out to design Winter One, my goal was to create a cooling and airflow focused SFF case. I hope this peek behind the scenes of Winter One's "CFD Driven Airflow Design" has given you a fair idea of what such a statement actually means. After a year of work, I’m pretty happy with the results.

VII. And finally a couple of updates on Winter One:

  1. Beta applications are still open, so if you want to be one of the lucky 3 that get to build early in Winter One, please fill out the form HERE. The application will close by Friday August 21, 2020!
  2. Website Version 2.0 is coming in the next couple of days, with more information about hardware compatibility, build instructions, and pricing.
  3. I’m just waiting on 1 more set of parts for the Winter One Prototypes, before I can make a full build video for you all to enjoy :)
  4. If any of you know Stephen Burke from Gamer's Nexus, I want to send him a review unit. I've emailed him but it probably get sent to his spam folder, so if anyone can get me touch with him, that would be amazing <3
  5. If any of you know Ali Sayed from Optimum Tech, I’ve also got a review unit for him, and wanted to send it over. <3
  6. Kickstarter is coming in September. You can sign up to get notified here
Edit: grammar fixes, etc.
submitted by WinterCharm to hardware [link] [comments]

Learning Matlab and CFD - Possible usage of Matlab in Aerodynamics design?

Hi!
I want to learn Matlab as well as CFD design and analysis. I will be doing a project where I will design a wing (with 3D CAD and 3D simulation analyzis with ANSYS) and I would like to use Matlab along the way so I have an objetive to learn this language aswell.
What are the possibilities ? I was thinking about simulations or processing and visualizing data, but not sure if that is the way to go to best learn this language.
Thank you!
submitted by Tuareg99 to AskEngineers [link] [comments]

haha ring go mach 2 (thanks solidworks cfd)

haha ring go mach 2 (thanks solidworks cfd) submitted by BitsBytesGaming to FTC [link] [comments]

I want to focus my career on CFD, any recommendations?

As I said in the title I want to be really good at CFD, so now I'm looking for some options to the near future that near future is MSc program, nowadays I'm finishing my BSc in Mechanical Engineering.
Do you guys recommend me any MSc programs that are really good at CFD, currently I'm looking at Danish Technical University, Technical University of Munich and KTH institute of Technology:
DTU MSc Mechanical Engineering, Industrial Fluids Engineering
TUM MSc Computational Mechanics
KTH MSc Engineering Mechanics, Fluid Mechanics Track
Every advice it's useful,
Thank you in advanced
submitted by yang7000 to CFD [link] [comments]

The Sony CFD-610: an enormous CD changer boombox.

The Sony CFD-610: an enormous CD changer boombox. submitted by JZ1011 to vintageaudio [link] [comments]

Why aren’t ya trading cfd’s and warrants?

Seems like you cucks like to play in penny stocks with a few bucks than leverage up to your eyeballs on some big players! Look into some warrants on ya cba tabs! Can get 10x returns trading blue chips!
Why yolo it your not gnna YOLO! Positions - oct 5500 puts Lots of short warrants!
submitted by jd_sleepypillows to ASX_Bets [link] [comments]

Airflow in Winter One -- A discussion about CFD in SFFPC cases

Airflow in Winter One -- A discussion about CFD in SFFPC cases submitted by WinterCharm to sffpc [link] [comments]

Trading212 setting favourable exchange rates for itself on CFD wins/losses?

I’ve just reviewed 50 CFD trades on Trading 212, pretty much even wins and losses.
I divided the average result of a trade in £ by the average price difference in $ at the open and close of a trade.
When I lost, the exchange rate was an average of £0.79 per dollar, which is bang on today’s exchange rate.
But when I won, the average rate was £0.77.
Of those 50 trades, the highest 20 rates were on losses, and the lowest 22 were on wins, with only a tiny bit of overlap in between.
Rates for wins ranged from 0.749 to 0.783. Rates for losses ranged from 0.778 to 0.813.
The only question is whether this is well known and/or standard industry practice.
Is it well known that they do this?
submitted by 23Heart23 to UKInvesting [link] [comments]

When has SpaceX ever used a wind tunnel or is it all CFD and trials?

submitted by lirecela to SpaceXLounge [link] [comments]

What's the best that could I buy for CFD simulations that is under $1000?

I don't mind buying second hand stuff or server grade components but I want to get the best performance while keeping the budget really low. Thanks a lot for your help.
submitted by Maccer_ to CFD [link] [comments]

MSc for CFD PhD?

I have BEng in Chemical Engineering and a few years of experience as a Process Engineer in design and industry both.
I am mainly interested in modelling in my job so thought of pursuing PhD in CFD later on. In my engineering degreee I enjoyed Maths and Fluid Dynamics courses the most. Recently I found myself interested in economics, economic models and in general I want to be more involved with what happens in the world. I feel like Economics pretty much gives you the idea of how the world works through mathematical point of view. I am confident about my interest in CFD, but I would like to expand my horizons so to say, studying Economics as well.
For now I am deciding on which Masters route to take to be able to succesfully set foot in the CFD field upon completion and the one that also trains the most relevant skills as well. I am now looking at joint Masters options: Applied Maths and Economics. Is it a viable option for someone with plans like mine? Will it give necessary background in both Maths and Econ or it will be half of each and none in total in the end? Also, I understand some coding, programming skills are required as well, I don't expect to learn to code by myself while being fully loaded with joint degree coursework. Is it an adequate fear or I don't need to worry about coding for now? I am asking as I've read a lot of conflicting information in the web. Please help.
submitted by irinrainbows to CFD [link] [comments]

CFDs, are they worth learning about?

i know CFDs are super high risk and everyone frequently warns newbies to stay away from them. But my question is, is the risk worth the reward? As in, is it comparable to options trading in the US, where you can potentially make a living off the money you make?
submitted by idntknww to UKInvesting [link] [comments]

cfd meme (please dont kill me I am learning )

cfd meme (please dont kill me I am learning ) submitted by lordmelvin007 to CFD [link] [comments]

Trading 212 CFD spread

Hey guys, noob here.
BACKGROUND: I'm fairly new to trading CFD, although I've spent some time in the investing section and I've read 3-4 books.
QUESTION: are trading 212s spreads fairly tight (because they don't seem it)?
I understand they won't be as tight as platforms that charge but is there a huge difference?
Are they pretty much the same as other free platforms?
submitted by f1fthsun to UKInvesting [link] [comments]

Buying ETF CFDs with XTB? any downside?

I am looking to buy certain US ETFs, not interested in margin/leverage. I have an acct with XTB. I see the only options to buy these are as CFDs.
Is there a downside to doing this? I don't fully understand if there are any margin implications or additional costs. Can someone clarify?

(or does anyone know a European ETF that is a good equivalent for VGT?)

Thank you
submitted by AtlasAstronomer to eupersonalfinance [link] [comments]

Difference in market price between CFD and invest

Just looking for clarification as to why there is such a difference in the CFD price and the invest price. I'm not talking about the spread but the actual price the stock is at.
So for example Gregg's stock is currently £13.49 on the CFD market but £13.59 on the standard invest account. I'm not talking about buy or sell price this is the price the stock is shown at in the market. What is the reason for this difference? Are they disconnected from each other?
Thanks for any answers
submitted by TurtlenecksandTits to trading212 [link] [comments]

I'm looking for ideas/inspiration for choosing my PhD research topic... I'm mainly interested in fluid structure/ CFD analysis kind of things in the space vehicle domain....I hope you will give me some ideas that are likely to be worked on to be improved in the relatively near future.

submitted by Resident_Pass_2530 to rocketry [link] [comments]

CFD Tutorial - von Karman Vortex Street  simFlow CFD ... CFD tutorial for Vortex Shedding - YouTube What is CFD Trading?  A Beginner's Guide to Contract For ... What Are CFDs? - YouTube Computational Fluid Dynamics (CFD)  RANS & FVM - YouTube

A contract for difference (CFD) is a popular form of derivative trading. CFD trading enables you to speculate on the rising or falling prices of fast-moving global financial markets (or instruments) such as shares, indices, commodities, currencies and treasuries. The CFD is a tradable contract between a client and the broker, who are exchanging the difference in the initial price of the trade and its value when the trade is unwound or reversed. CFD Store (307) 778-1424. Headquarters (307) 778-7200. CFD Old West Museum (307) 778-7290 ... This has resulted in unplanned preventive maintenance during the CFD’s First Week To Give promotion. We are actively working to bring the system back online promptly and safely, and will update all of our partners and donors as soon as we are able to process new donations and disburse the Starbucks gift cards awarded as part of this campaign. CFD is a wholesale distributor of Farm, Garden and Pet supplies including these exclusive brands: . CFD does not sell directly to the public. If you see something you like, use our CFD Dealer Locator to find a dealer near you.. More about CFD »

[index] [1773] [1215] [3444] [6812] [3749] [3482] [4847] [1033] [2052] [5183]

CFD Tutorial - von Karman Vortex Street simFlow CFD ...

Learn about contracts for difference! Your capital is at risk. This is 2nd part of CFD video lecture series. Here method of solving Navier Stokes equations using Reynolds Averaged Navier Stokes equations, Necessity of Tu... In fluid dynamics, vortex shedding is an oscillating flow that takes place when a fluid such as air or water flows past a bluff (as opposed to streamlined) b... Stock trading can take many forms and many traders confuse the two main types: Equity trading (also known as trading real stocks) and CFD trading (or buying ... Subscribe https://www.youtube.com/IGUnitedKingdom?sub_confirmation=1 Trading contracts for difference (CFDs) is a popular way to speculate on rising and fa...

https://forex-portugal.forexdomain.pw