Physics 34 Fluid Dynamics (3 of 24) Viscosity & Fluid Flow: Reynolds Number (Re)

[@jackwilliams8986]

This guy is a legend, and this is the reason why I choose engineering. I love the way you teach, and sometimes hate the way universities teaches it.

[@dawsondemontiney1247]

This guy helped me get my engineering degree thank you Michel

[@3E37]

@@dawsondemontiney1247 did you send him some money ?? for the help

[@n7pako367]

This guy is great, a 3 hour class explained in less than 8 minutes... Why do teachers make everything so complicated?

[@saiguddati2303]

Sorry smart

[@dorritdidi5543]

”if you can't explain it simply you don't understand it well enough” Albert Einstein Thank you for making this so simple to understand

[@MichelvanBiezen]

Thank you. Glad you find it helpful.

[@MS-xs2ts]

thank god finally I've learned Reynolds number. this was giving me headache for my project. you are a legend

[@coolmonkey619]

This is a life saving during Covid

[@MichelvanBiezen]

Glad we can help.

[@avatarmobile8576]

Mr. van Biezen. I am witnessing building code requiring a drain pipe vent at all sink connections, where a p-trap is used. I ran across this due to improperly or faulty installations of these vents, and the city sewer gasses running back into the sink counter cabinet, and obvious stink. I understand that these vents were added due to a outgoing flow of liquid effluent, through suction, pulling the p-trap completely dry, removing the benefit of the pooled liquid seal. Should this not be a result of incompatibility of our fluid dynamics, with the diameter of the piping? Should this century old basic plumbing apparatus not be updated with the benefit of revised diameters and dimensions, such that no suction or outflow should ever be of such velocity as to drain this liquid seal from the low point of the p-trap? I think the answer is yes, and the solution to the problem is a larger diameter at the tail end of the trap, and or an additional height depth int he design. What say you, I's love to see you nail that problem, complete with fudge factors.

[@SIMEONOVVASIL]

Hello Mike, can you do simple tasks right after each lecture, so we can check what we have learned? One or two, simply to train the knowledge we gain. I am very grateful for your teaching skills and very concise eLectures!

[@maurohenriques2479]

When you have a fluid that is flowing inside a pipe and that pipe has a pipe within (like in a heat exchanger, double pipe), witch diameter do you use to determine the Re of the fuid that is going inside the large pipe and outside the smaller piper? thank you great video

[@minhsiachen8186]

Really appreciate your explanation! You make Fluid Mechanics so 😎. I particularly like the way you build up to the derivation from fundamental science 👍

[@MichelvanBiezen]

Glad to help!

[@speedbird7587]

Very nice! But the Reynold's number is a result of nondimensionalization of lets say the Navier-Stoke's equations, but why really we are interested in nondimensionalizing differential equations? Thank you

[@MichelvanBiezen]

It is just an approximation of the type of flow you can expect. (It is not an exact value)

[@sherbanikcelvesel]

Hello, How does Flow change in different pipe diameters.? For example when flow travels in 2 diferent diameters pipe. What will be the flow in a big diameter pipe and what will be when enters in a small diameter and when will be in small diameter?

[@carultch]

Are they in series or parallel? If they are in series, the mass flow rate in both has to be the same (i.e. continuity). The flow will trade average velocity for cross sectional area, as it passes through different sized pipes. The pressure drop will be additive between both pipe sections. If they are in parallel, they will have the same pressure drop, and mass flow rate will add up between the two paths.

[@sausamaresh1]

great basic lecture

[@MichelvanBiezen]

Thank you. Glad you think so. 🙂

[@gs2298]

Great work

[@MichelvanBiezen]

Thanks

[@gs2298]

I like the way you teach and you have amazing voice,

[@gs2298]

I Like this phase welcome to lecture online

[@surendrakverma555]

Excellent Sir.Regards

[@salahalmafrjy2095]

hi whats the equation for particle Reynold numer and Reynold number of fluid

[@halbdaf4615]

why i did the different unit when putting them all together (plv/u)

[@akuadam8585]

Excuse me, Sir What about the reynold number on the arranged plate?

[@MuhammedMuhammed-ci2pr]

thank you sir thats help me a lot

[@MichelvanBiezen]

Glad it was helpful.

[@hi_is_this_clorox_bleach]

How do you calculate for variable diameter??

[@MichelvanBiezen]

Note that we did not take into account the diameter, friction forces with the sides and change in velocity as a function of radial position. These are covered in other videos.

[@hi_is_this_clorox_bleach]

@@MichelvanBiezen thank you very much will be delving into the series

[@anjaliladi1997]

thankyou very much! it was very helpful

[@sebastianc1639]

Genio!! from Argentina!

[@MichelvanBiezen]

Welcome to the channel!

[@marifea.1905]

You are so AMAZING sir. Godbless you!

[@dylanparker130]

unbelievably helpful - thank you so much

[@MingRenWilliam]

Thank you! Helped me understand Reynolds Number well

[@Huuuhhh]

Can the characteristic length be the diameter of a descending sphere?

[@axelb15]

Hello sir, I'm trying to derive the Reynolds number for a sinking sphere. Because Re is the ratio of intertial to viscous drag forces, and in a sphere inertial: 0.5*Cd*rho*pir^2(Ac)*v^2, and viscous force is: 6*pi*r*mu*v. When I do the ratio I get: (Cd*rho*v*r)/(12*mu) instead of (rho*v*2r)/mu. What did I do wrong/ is my equation correct? Why is it like this/ did I misuse the equations? Thank you!

[@PankajRaj-ps5jx]

Fabulous sir...... Thanks....

[@1400740]

Very useful lecture. Thank you

[@jerusalemgeremew8704]

What about cavitation and its worked examples

[@mcebm14]

sometimes the viscosity come with a unit of cp sometimes the flow rate comes with kg/sec or m^3/min or sec

[@bassemghorab]

Depends if it's mass flow rate or volume flow rate

[@vinaybalineni8906]

awesome explanation ..thank you very much sir

[@adityawankhede4634]

Thanks a lot for making this video

[@bluebloo5574]

Love you ! u are a legend.

[@yonasnegusse5294]

Thank you.

[@MichelvanBiezen]

You're welcome!

[@ibrahimjaafar6172]

what happens if Re = 1 ?

[@dgchem06]

Dear sir, can you to explaint us for ' how to calculate of viscosity using Cup'?

[@MichelvanBiezen]

The viscosity of a fluid is usually determined experimentally by dropping a know object like a metal sphere (diameter and density known) and watch how long it takes to reach terminal velocity and what the terminal velocity is. There are some videos in the set that give you more information on this.

[@muhammadrajendra6386]

hey, i am struggling right now, my reynolds number is only 4.7 - 6.5, while the prandtl is higher the problem is i dont know which equation to find my nusselt number. (convection in a tube)

[@muhammadrajendra6386]

most logical for me is to use dittus-boelter (heating) but the requirement is reynold number higher than 6000

[@royrosales81]

Great explanation. Thank you very much!

[@farisal-amer7635]

Thank you!

[@samarhossameldinahmed3814]

Thanks a lot, it was great.

[@tomcruise9317]

Density increases will make the fluid to slow down how can it increase turbulance

[@MichelvanBiezen]

That is not how to inerpret the equation in the video. All other parameters kept the same, the fluid with the highest density will have the highest Reyhold's number, and thus will more likely have a turbulent flow.

[@tomcruise9317]

@@MichelvanBiezen equation it ok but if you think pratically high density will make flu8d to slow down only sir

[@sandiladhikari6305]

2000-4000 Reynold's number were supposed to be transition flow I think. Anyways it was a really good teaching.

[@MichelvanBiezen]

Yes, it depends a number of things such as type of pipe, diameter of the pipe, etc.

[@suvendumondal8218]

thank you very much..........for helpfull video

[@sharefhamoud4416]

Thank you💙

[@NaveenReddy-hn2yp]

Thank you very much for the detailed explanation.. :) :)

[@reluctantchemist]

nice explanation

[@farhanalshammari8696]

Thanks

[@saidunany]

sir ,, if the Re=1........... does the viscous force =inertial force yes? or no? plss give me explanation

[@MichelvanBiezen]

Note that I placed the terms "inertial force" and "viscous force" in quotation marks. Strictly speaking these quantities are not forces since they do not have units of force. But it gives us a means to try and understand the concept of the Ryenolds number and what it represents.

[@DukeNero]

I think he is asking "what happens if inertial force equals viscous force"

[@Ethers_World]

thank you

[@er.ajayyadav2705]

Thank u sir

[@abdimajiid5351]

thanks a lot

[@DKomala]

thank you so much!

[@РустамБегисов]

Thank u very much

[@engineeramitbhaskar4121]

Wow sir thanks a lot

[@tag_of_frank]

man I watched every video and you never spoke about determining characteristic length ugh.

[@oghenemoses8839]

How can one person have all this knowledge?

[@MichelvanBiezen]

It comes from continuing to study a wide variety of subjects over a lifetime. But knowledge does not equate to wisdom which is far more important and which I am still trying to acquire.

[@aaroneley1412]

Why are universities a thing

[@frankbooth8003]

Thank you! :)

[@yasseralg3928]

Why do fluid mechanics books seem very old and not much effort is put into making them look appealing?

[@MichelvanBiezen]

Sometimes those old books are the best. I have some books from the 1950s that contain material that no longer is placed inside the newer editions.

[@PankajRaj-ps5jx]

I m indian Mr PANKAJ Yadav

[@MichelvanBiezen]

Welcome to the channel!

[@iamrajesh7520]

Re ante amitii

[@alexfido2935]

hahaha. he sounds like gru

[@abdimajiid5351]

Thanks a lot

[@sagaljp7148]

Thanks

[@MichelvanBiezen]

You are welcome.