Rotational Viscometer: Measurement of Dynamic Viscosity (Newtonian and Non-Newtonian Fluids)

[@FluidMatters]

All the videos for this introductory Fluid Mechanics course are available at: www.drdavidnaylor.net/

[@colinwarn4606]

Just wanted to extend my thanks for putting together a great KZbin series on Fluid Mechanics. Been a couple years since I've taken the class, the series has been a great refresher on the theory, in addition to tying it to some very informative experiments that visually cement the concepts 🙂

[@FluidMatters]

Thanks. Great to hear!

[@Jey187]

For anyone who may not know about the weird behavior of Corn starch mix with water, at 6:56 he is not stopping his motion, the surface actually get hard when you try to inset something quickly in it.

[@CalvinWi41]

Can you tell me why you take the speed of 30 rpm. How is this determined? I know that according to the DIN EN ISO 2555:2018 standard, the full scale value (M%) should be between 45 and 95 %. The values I determine sometimes vary enormously depending on the spindle and the speed. Thank you for the great video and I hope for an answer soon :)

[@FluidMatters]

This is a demo for undergrad engineering students learning about the general concepts of viscosity and Newtonian/non-Newtonian fluids. This video is not about "best practices" for rotational viscometers. It makes sense to follow ISO standard, of course.

[@thomasvloemans9253]

Great video!

[@antogodwin2330]

How do we calculate the shear rate?

[@FluidMatters]

You can't get that information from this type of instrument, as far as I know. (If the instrument provided the value of the torque, you could estimate the mean shear rate at the surface of the spindle.)

[@mohammadfallahzade2110]

thank you you are a great teacher

[@sarahnurfitriani1858]

Is it okay if i remove the spindel guard when measuring viscosity?

[@FluidMatters]

I think you can. (I'd have to check the manual to be 100% sure, which I'd bet you can find online.) It might change the calibration slightly.

[@tunayel4613]

@@FluidMatters Sir, have you checked the manual? What is the purpose of the spindle guard?

[@cioccolatamania3622]

I just tried doing it for water , which is a newtonian fluid, right? I noticed that the mPa-s(also centipose, unit of viscosity) decreases with the increasing rotational speed. Is this normaL??

[@FluidMatters]

Water is newtonian. This type of instrument requires fully laminar flow. The viscosity of water is very low. So, maybe you are getting turbulence in the boundary layer at higher rotational speeds, which would result in an inaccurate measurement. Just a thought.

[@cioccolatamania3622]

@@FluidMatters ahh I see thank you.

[@EhabAbozaid]

nice video. thanks for sharing

[@engr.frederickoshomogho620]

Thank you for sharing

[@dilshodbekeshboriyev5398]

Thank you

[@mangobliss13]

Thankyou!