The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water.Viscosity can be conceptualized as quantifying the internal frictional force that arises between adjacent layers of fluid that are in relative motion. For instance, when a viscous fluid is forced through a tube, it flows more quickly near the tube's axis than near its walls. In such a case, experiments show that some stress (such as a pressure difference between the two ends of the tube) is needed to sustain the flow through the tube. This is because a force is required to overcome the friction between the layers of the fluid which are in relative motion. So for a tube with a constant rate of flow, the strength of the compensating force is proportional to the fluid's viscosity.
A fluid that has no resistance to shear stress is known as an ideal or inviscid fluid. Zero viscosity is observed only at very low temperatures in superfluids. Otherwise, the second law of thermodynamics requires all fluids to have positive viscosity; such fluids are technically said to be viscous or viscid. A fluid with a high viscosity, such as pitch, may appear to be a solid.
Homework Statement
Hello, I am doing a project which requires damping and have decided to use some viscous damping. It is simply on a hacksaw blade with a weight on the end. Therefore, other than just trial and error I would like to calculate the range of viscosities that may be useful for...
I was just wondering. Say you have two different liquid with two different viscosities (water and oil, etc). If you have them in two different containers, and having the same amount in each container, say 500 mL. You heat them both to some temperature, say 100 F. Since liquid expands when it is...
Is there an equation that relates viscosity of water to temperature? If not, is there a reliable table somewhere on the internet? I'm searching for the viscosity at 20°C ± 3°C.
Since there are no frictional forces acting on the superfluid my intuition would tell me that there is no way for the liquid to "climb" the sides of a container. Obviously though, intuition isn't the best thing to go by when it comes to superfluids. I'm just wondering: what mechanism drives it...
hi, this is the first time i learn about viscosity, but I don't know where to start with this question:
At 18.5°C, the viscosity of 1 wt% aqueous sugar solution is 1.025 times higher than the viscosity of pure water. At the same temperature, the diffusion coefficient of the sugar molecules is...
Hi, even though this is my first post, Physics Forums have helped my a over that past couple of years. Just searching old PF threads usually gave me the answer I was looking for. So thanks.
I am currently doing Advanced Higher (Scottish Qualification) Physics Investigation on Viscosity. During...
What are the factors that affect viscosity of incompressible Newtonian fluid?
Here is what I think:
Temperature:
When we increase the temperature of a fluid (controlled volume) the frequency ofintermoleculer collisions increases. Does this mean viscosity decreases? And if so, does...
Hey guys,
I am researching the viscosity of different liquids. I want to use an acoustic method to determine the acoustic viscosity. In some readings I figured that this can be done by using two Piezo sensors. The two sensors are inserted into water, liquid, etc. Transmit sensor (sensor A)...
Homework Statement
Find the viscosity of water given that;
flow rate (cm^3 s^{-1}) = 2.0
height from tube (m) = 0.1
l (m) = 0.2
r (mm) = 1
\rho = 1000
g = 9.81
Using the equations;
x = \frac{Flow Rate}{Height}
x = \frac{\pi \rho gr^4}{8l\eta}The Attempt at a Solution
Okay so first, and...
Homework Statement
PLEASE help! I really should be able to do this but am so stuck:
Two plane disks, each of radius 5 cm, are mounted coaxially with their adjacent surfaces
1 mm apart. They are in a chamber containing Ar gas at S.T.P. (viscosity
2.1×10−5 Nsm−2) and are free to rotate...
I've managed to calculate the viscosity of glycerol to be about 1.9 P. Google says it's supposed to be 1.5. Could I say that evaporated water has caused the glycerol to become more viscous than it should be? (It could just be a thicker glycerol but I'm just looking things to blab on about)...
I'm trying to find the viscosity of some glycerol that we dropped various steel balls down using the equation:
V = [2r^2 (p – σ) g] / 9η
I put in these values:
p = 7800 kg m-3
σ = 1200 kg m-3
g = 9.8 m s-2
And ended up with the equation. η = 129360r^2 / 9V
My problem is that I...
Homework Statement
The change of viscosity with temperature can be described using the general equation
ln(µ) = A + (B/T), where µ represents dynamic viscosity, T represents temperature (Kelvin), and A and B are constants.
a) Find the values of A and B for raw milk, using the viscosity...
How to calculate the dynamic viscosity of air at high alttitudes,i want to calculate it at hight 4000m abovesea level at that hight the temp. is 262 kelven degrees.
Any thoughts?
finally in my search to understand why the boundary layer separates from the surface of a baseball I have come to understand that the reasons for the separation of the boundary layer from a baseball is incredibly similar to the separation of the boundary layer from a wing of an airplane after...
a question on boundary layers viscosity and air seperating from a ball
I have a few questions that have to do with a viscosity on the surface of an object, the boundary layer and the boundary layer separating from the surface of a baseball!
1) my first question is if we had a stationary...
1. Homework Statement
where:
l = the length of the tube in cm
r = the radius of the tube in cm
p = the difference in pressure of the two ends of the tube in dynes per cm2
c = the coefficient of Viscosity in poises (dyne-seconds per cm2)
v = volume in cm3 per second
pi =...
Hi all.
I am learning things about incompressible turbulent mena flow.
I am completely confused by these terms: moleculr viscosity and eddy viscosity.
What are they?
Is molecular viscosity the same as the visocosity of the fluid we often use?
And what exactly is eddy viscosity? I know it is...
Homework Statement
A flat plate viscometer consists of a disc of diameter 50mm rotating at 300rpm in close proximity to a fixed horizontal plate. When the gap between the plates is 0.1mm, it is found that the torque required to drive the disc is 0.2Nm. What is the viscosity of the liquid...
Hi guys,
For a prac we did, we are given the properties of a particular oil.
Density (kg/m^3) = 876
Viscosity (Ns/m^2) = 20.0x10^(-3)
I believe it is the dynamic viscosity. Now is this viscosity correct? Or should it be 2.0x10^(-3)
Homework Statement
A shearing force of 100 dynes is applied to the side of a rectangular plate of 5 x 10 cm dimensions placed on top of a 0.5 mm high column of Newtonian fluid that is initially at rest. As a result of the shearing force, the plate moves at a speed of 11.2 cm/sec. What is the...
How good derivations are there for the viscosity term \nu \nabla^2 u_i, that contributes to the acceleration of fluid, in Navier-Stokes equations? I can see that this term is intuitively reasonable. If I wanted to approximate the velocity of the fluid in an environment of some point...
Homework Statement
Two identical vertical cylindrical vessels of cross section α are joined at thir bases by a narrow horizontal tube of length l and internal radius r.A liquid of density d and co-efficient of viscosity λ is flowing slowly from one vessel to the other through the...
I need to do some head loss calculations for pumping diesel fuel or No. 2 fuel oil from a storage tank to an emergency generator. I see in many places that diesel fuel is specified to have kinematic viscosities of 1.3 to 4.1 cSt at 40C. However, under worst case scenarios, this fuel is likely...
Homework Statement
Hi guys, I need to find the flow of water at temperature of 350K. I had to do this, but for air in the same problem...but I can't find an equation to account for the viscosity change, due to temperature rise. My book lists it at 86.0 x 10^-5 Pa*s @ temp 300K...
Could anyone tell me what the viscosity and density of glycerol are at 294K?
This may be the wrong forum but technically it is physics cousework even though I am asking for chemistry
I got the following value for the viscosity 1.27Pa.sec.
correct?
Viscosity Woes :(
Hi,
I'm conducting a Physics Investigation where I'm changing the temperature of Motor Oil and seeing how the change in temperature affects viscosity of the oil. I am measuring the terminal velocity of the sphere in the oil (V). I'm Using Stokes' Law Equation: F=6piRNV...
Hi,
I have a question about the viscosity of fluids: If I know the viscosity of one fluid, say 1 Pa.s, and I add a portion of water (say for example 1 part water to 9 parts fluid), viscosity 0.89 × 10^-3 Pa.s, what is the viscosity of the new mixture? I have done an experiment for school where...
Hi. This is a two part question, I'm pretty sure about the first bit but in the second part my answer seems a bit weird. Not the order of magnitude I was expecting. Just wondering can anyone confirm or deny my suspician? Point me in more correct direction if I am indeed wrong. This isn't for...
In my course of Acoustics, in the chapter about fluid dynamics, we derive an expression for the stress tensor similar to this one, and then it is said:
"It is convenient, to write this expression in a slightly different form, in which eta and lambda are replaced by other constants"
The...
Does anybody know why viscosity changes with temperature?
I'm expected to do a short explanation or suggestion for my homework of why this happens but to be honest I'm not sure. :confused:
The only reason I can think of is higher temperature means more energy therefore less internal...
I'm trying to work out the viscosity of oil at various temperatures. I've got all my results, but when I try to work out the viscosity I get some really far out answers. What region would you expect the viscosity of oil room temperature to be? I get this result for viscosity of oil: -1330245.26...
Say the reaction is like:
A + B <=> C + D
and i know the individual concentrations of the reactants and products.
Is there any equation to find the viscosity of the system?
Any softwares to simulate??
I have been reading a number of aerodynamic texts, and it seems that everything in a fluid (gas) is transmitted by molecular collisions.
Pressure is a result of molecules colliding with each other and the walls of a container
Viscosity is caused by collisions between molecules in layers...
I did an experiment to calculate viscosities of various ethanol concentrations, 0% to 100%
the graph is parabolic, and therefor the highest viscosity is 50% concentration
i don't understand why, since seperately water and ethanol are closer to 1 centipoise well ethanol more and water less...
hi all just doing some questions and come along these two which have me stumped. There multiple choice questions but id rather know the working out to them as i have exams in a couple of weeks. thanks.
1. The mass of a hot-air balloon and its fully loaded basket is 500kg excluding the air in...
hello, i need to know about the viscosity of liquids i.e. the science behind it. most websites i looked into did not help at all!
also, i am doing an experiment based on the viscosity of liquids and have five liquids to choose from : honey, olive oil, ethanol, water, and corn syrup. please...
Viscosity and Upthrust...
Viscosity and upthrust are both forces which occur in liquids, and must both rely on electrostatic effects. So what is there difference between them? What causes these 2 distinctly different effects?
Thanks in advance. :smile:
For AS Level physics I had to do some coursework on the viscosity of Honey. I found out that as the temperature of the honey increases, its viscosity decreases.
I drew the conclusion that, when a substance is heated, its molecules move farther apart and faster, so therefore, if the molecules...
Why is the flow behaviour or viscosity important in the case of polymer?
This question is given when we had lecture about flow behaviour, viscosity, and rheology.
Thanks a lot!
Hi,
Im doing an experiment to determine the viscosity of glycerol this is my collected data:
Data:
Sphere radius: 0.8 cm
Sphere mass: 16.3 g
Sphere voume: 2.14 cm -³
Sphere density: 7.62 g cm -³
Glycerol density 1.26 g cm -³
Sphere Terminal Velocity: 23 cm/s
Light Gate...
Hello again. My friend is also doing his science fair project and he has trouble thinking of ways that we can apply "relationship of heat capacity and viscosity" to everyday life. His experiment is basically just to examine how much the temperature of fluids with different viscosities are...