Viscosity Definition and 254 Threads

Hello Forum, I have some conceptual doubts about shear viscosity and would like some help if possible. In general, viscosity depends both on temperature and on shear forces (more strongly on shear forces). "Shear viscosity" is the viscosity that a molten plastic assumes when the molten fluid...

Homework Statement Hi there. For my A2 physics coursework I have been doing an experiment into stokes law, in which I dropped ball bearings of various diameters into a tube filled with a liquid, worked out their terminal velocities and then used Stokes Law to calculate the viscosity of the...

I was wondering, a ballpoint pen ink droplet is droped on water, it floats and moves, why? Is it density, viscosity, surface tension or something else. I am pretty stuck

Homework Statement Water (η = 1.00E-3 Pa·s) is flowing through a horizontal pipe with a volume flow rate of 0.0125 m3/s. As the drawing below shows, there are two vertical tubes that project from the pipe. Assume that H = 0.0458 m and L = 0.738 m. Calculate the radius of the horizontal pipe...

Any help with this basic college problem. Homework Statement The following readings were obtained in an experiment to find the coefficient of viscosity of water n by measuring the rate of flow of water through a horizontal capillary tube. Diameter of capillary tube = 1.40 mm Length of...

I understand that the dynamic modulus of a material is measured by inducing a sinusoidal force and measuring the strain response. Usually one gets a value for the storage and loss modulus. However, I don't understand how one would "quantify" how viscous a material is. I know a viscous material...

Hello Forum, I have two polymers (both in pellet form). Their spec sheet shows that the two polymers have different intrinsic viscosity IV. There are so many definitions of viscosity (dynamic, intrinsic, inherent, etc.) In general viscosity and density are two independent properties of a...

Homework Statement I have been given an experiment to perform, whereby I drop steel ball bearings into a glass measuring cylinder, and time how long it takes for the ball bearing to fall a set distance. From this I should be able to work out the viscosity coeffienct of the glycerol. I have...

Homework Statement Using the provided data for viscosity coefficients of C2H5OH (ethanol) as a function of temperature, find the constants A and B for this substance using the following equation. Viscosity coefficients of ethanol: T (K) - \eta (cP) 273.15 - 1.773 293.15 - 1.2 313.15 -...

Homework Statement Think of a fluid between two plates at a distance d from each other in the z-direction; then slide the top plate at a constant speed v_0 in the x-direction while holding the bottom plate still. The fluid pushes back, so you need to apply a force F in order to keep the plate...

Hello friend... I have confusion in understanding the concept of viscosity. Please help me. Viscosity is the property of the fluid which offers resistance to the movement of one layer of fluid over another adjacent layer of the fluid. Here both top and adjacent layer causes shear stress on each...

i know the relation between these two. with increase in pressure, the viscosity of liquids (expect water] increases while that of gases is practically independent of pressure. The viscosity of water decreases with increase in pressure. i want to know the reason behind this.

wHomework Statement water at 20 degrees celsius is flowing in a horizontal pipe is 20 m long. The flow is laminar and the water completely fills the pipe. A pump maintains the gauge pressure of 1400 pa at a large tank at one end of the pipe. the other end of the pipe is open to the air. the...

Homework Statement An auto lift consists of a 55.56 cm diameter ram which slides concentrically in a 55.58 cm diameter cylinder (see Figure 1). The cylinder engages a 2.8 m length of the ram at all times. The annular region between the ram and cylinder is filled with viscous oil. The...

Homework Statement Two flat plates are oriented parallel above a fixed lower plate as shown below, The top plate, located a distance b above the fixed plate, is pulled along with speed V. The other thin plate is located a distance 0.3b (cb) above the fixed plate. This plate moves with speed...

Homework Statement The velocity distribution of a fluid in two 0.3m long rotating cylinders is given by u=0.4/r-1000r (m/s). The diameter of the cylinders are 2cm and 4cm. If the inner cylinder rotates at 500rpm the power on the inner cylinder is measured to be 1Watt. Find the viscosity of the...

Homework Statement having problems differentiating Homework Equations Tw ( wall shear stress)= -U(viscosity)*du/dr been given u as 2V(1-(r/r)^2) The Attempt at a Solution i substituted u in and got d/dr (2V(1-(r/r)^2) i tried to multiply out the minus sign and 2V and got...

I am looking for a book which describes viscosity on a molecular level. The problem is that I don't have enough experience to make a wise selection. If anyone has some good pointers please share.

Relation between Cooling rate and Viscosity Hi all I have a situation where i have a molten Aluminium Copper alloy melt poured in a mould to be solidified. This means, the mould temperature is lower than than than the poured melt. I am thinking about a relation which associates temperature...

What are the relationships between these 3 properties of a fluid and how would you calculate say the density when you know the viscosity and specific gravity?

Hi, When solving for example Shallow Water Equations, the system itself is hyperbolic. Usually when dealing with non smooth solutions people add artificial diffusion to the momentum equation. Can anyone suggest papers or book, where they explain why it helps and why we can consider such...

Homework Statement The viscosity of a fluid is to be measured by a viscometer constructed of two 75 cm long concentric cylinders. The outer diameter of the inner cylinder is 15 cm and the gap between the two cylinders is 1 mm. With the outer cylinder fixed the inner cylinder is rotated at 300...

Homework Statement You are going to examine the viscosity of a fluid by dropping a ball bearing into a cylinder of fluid and measuring the fall time. You will use a ruler to measure the height, h, of the fluid column, and a stop watch to measure the fall time, t. The ruler and stop watch...

Viscocity of glycerine is high than that of oil then why it can't be used in hydraulic brakes..?

Does a stronger engine need a higher viscosity fluid? What's the reasoning behind this?

Pascal-seconds is a unit of viscosity. Why? I know that viscosity represents the thickness of a fluid, or its ease of flow, but I don't understand why that is represented by these parameters.

Hello, what forces causes density and viscosity in a fluid ? I thought oil was more dense than water but it is only more viscous. I suppose a very viscous liquid has strong forces interacting between the molecules so they became closer and shouldn't density increase too ? Thank you

Hello, Homework Statement I am trying to find an expression for the energy transferred into heat due to friction between layers of viscid fluid. I am provided with the following diagram (see attachment), and am instructed to first find the force at both ends of the cylinder exerted on the...

Homework Statement Hi guys, I'm pretty new here, and long story short, I'm struggling a bit on a fluid mechanics question I've been doing for some revision. A shaft 70 mm in diameter is being pushed at a speed of 400 mm/s through a bearing sleeve 70.2 mm in diameter and 250 mm long...

Hello, I have recently conducted an experiment to measure the viscosity of some liquids using the falling sphere method and a high speed camera. For most of the measurements this is fine since the spheres reach terminal velocity and so it is easy to calculate the viscosity from: v =...

I'm in search of a material that decreases in viscosity with acceleration. In this case, I really mean decelleration, but a change of velocity nonetheless. My questions: 1. Could such a material exist? Does Such a material exist? If so, what is it? 2. Would a material with said properties...

Dear all, Can anyone explain the the phase lag between force and displacement in single degree of freedom forced vibration with viscosity damping? The response of phase angle derived by mechanical vibration as below ( assuming force is excited harmonically) : Phi(ω) = arctan( C*ω / ( K...

What factors affect the speed of sound besides the temperature? Does viscosity affect the speed of sound? Thanks

Hi,I don know if my question will be clear,but I will try it.So,I m wondering how was derive this equation: viscosity=viscosity(known liquid)*density(known from table)*time(liquid will get over one point of Ubelohde viscometer to second point of viscometer(unknown liquid)/density(known...

How do I tell what the coefficient of viscosity is of SAE 10W-30 oil? It is at 25 degrees C. My book says that multigrade oils like this have a non Newtonian blending additive. This doesn't mean I have to treat the substance as non Newtonian does it? Any help would be appreciated.

Homework Statement Attached. I am working on part (i). What is the resistive force? Shear stress= μ*(du/dy) = μU/l = F/A Since the force is up and down, it causes a shear stress, thus area is parallel to the force and thus it is the 4 faces B*L Thus, A=4*B*L → F=μ*U*A/l =...

I'm just a layman trying to understand some information and a chart I'm reading about viscosity as it relates to practical lubrication choices. There's an article here at MachineryLubrication.com on how to choose the proper grease. First, I would like to make sure I am reading this chart...

Homework Statement At What temperature will air get a larger kinematic viscosity than crude oil? Please explain step by step. I believe we have compare the viscosity of air and the oil using the formula: kinematic viscosity = dynamic viscosity / density Homework Equations inematic...

It is stated that kinematic viscosity is the ratio of dynamic viscosity to density. can anyone elaborate it further that what are the uses of both types of viscosities and why we differentiate them.does dynamic viscosity reates with static fluid?

The following question is on viscosity, and I feel like I am looking too much into the problem, but I am having a very hard time getting started! The total space between stationary boundaries is 1cm. Ethylene glycol is placed on the left side, and propylene glycol is placed on the right...

Why the speed of water in the middle of the smooth flowing stream is high than its speed on the sides? Is it due to Adhesion or cohesion forces or viscosity or Bernoulli principle holds here? Kindly tell me exact reason .

Problem Statement: Blood is a pseudoplastic fluid that has a variable viscosity at 37 °C that depends on the percent composition of hematocrit and plasma. It will usually range between 3 x 10^-3 to 4 x 10^-3 Pa s. A small sample of blood is tested in a viscometer and the following results are...

Homework Statement I used a home made falling sphere viscosimeter to obtain: terminal velocity = 0.06216 ms^-1 I used a micrometer to obtain: radius = 0.001835m and, because my value for glycerol viscosity was way off the known value of 1.495 Pa s, I decided to measure the density of the...

Hi all This is my first time here and I'm hoping first that I have reached the right forum for my question and that someone out there can help me! I am trying to model the energy dissipation of what is effectively a mass spring damper where the spring and damper are modelling a polymer. I...

Who said approximately: The viscosity of the aether / vacuum state / zero-point-field / or whatever is ridiculous / ridiculously large / great / high ? This person had computed it using i.a. the c0 value of light speed. What else was in the formula ? / Grateful for info...

The linear drag coefficient is a function only of object size and medium viscosity. Multiply sources say viscosity of air is independent of pressure and density. How can the linear drag be independent of density of the medium? It seems like less dense medium should mean fewer collision and in...

I'm working on a project at work that requires some tribology/fluids calculations that I don't know if are applicable to me or not. For this scenario, one of the tests will require me to assume hydrodynamic lubrication where oil is completely separating the 2 surfaces. I have a sliding...

I am currently using garder tubes to measure the viscosity of a material (mainly adhesives and some wax) in the process of manufacturing Newtonian as well as non-Newtonian materials. I am looking for an alternative method that is less qualatative in an attempt to decrease the defects per...

In college we measured the viscosity of microcrystalline cellulose and used the result to determine its degree of polymerisation. Is the viscosity of a polymer directly proportional to its degree of polymerisation or something? In other words the bigger the polymer, the more viscous it is? Does...

Hello all ! Why on a surface of the Earth the calm is possible? The Earth rotates about (аround) the axis. Why air molecules are motionless concerning the Earth?