What is the force required to keep the plate moving at a constant speed?
A shear stress, t = (F/A) must be applied to the system to keep the top plate moving at a constant speed U. This stress is related to the viscosity, m, of the fluid and the velocity gradient or strain rate (U/h): t = m (U/h).
Which force is consider to calculate power required to keep plate in motion?
u = V = v/h. The gap height, h is 5 mm and the space is filled with oil (specific gravity = 0.86, viscosity m = 2 × 10–1 N-s/m²). The bottom plate is stationary and the top plate moves with a steady velocity of V = 5 cm/s. The area of the plate is 0.25 m²….Correct Option: C.
| = μ. | v | .A |
|---|---|---|
| h |
What is the formula of viscous force?
For Newtonian fluids, viscous or shear forces in the fluid are described by a relationship between the stress (force/unit area) between the fluid layers which results in a shear of the velocity field in the fluid as follows, τ = μ · ∂u/∂y, where τ is the shear stress in the fluid, ∂u/∂y is the rate of strain of the …
What is the driving force for Couette flow?
In fluid dynamics, Couette flow is the flow of a viscous fluid in the space between two surfaces, one of which is moving tangentially relative to the other. The relative motion of the surfaces imposes a shear stress on the fluid and induces flow.
How do you calculate drag force in physics?
For larger objects (such as a baseball) moving at a velocity v in air, the drag force is given by FD=12CρAv2 F D = 1 2 C ρ A v 2 , where C is the drag coefficient (typical values are given in Table 1), A is the area of the object facing the fluid, and ρ is the fluid density.
How do you find the net force?
Net force is the sum of all forces acting on an object. The net force can be calculated using Newton’s second law, which states that F = ma, where: F is the net force. m is the mass of the object.
How do you calculate viscous drag force?
Fs = 6πrηv, where r is the radius of the object, η is the viscosity of the fluid, and v is the object’s velocity.
How do you calculate the viscosity of a liquid?
Viscosity = (2 x (ball density – liquid density) x g x a^2) ÷ (9 x v), where g = acceleration due to gravity = 9.8 m/s^2, a = radius of ball bearing, and v = velocity of ball bearing through liquid. Plug your measurements into the equation to calculate the viscosity of the liquid.
What is the difference between Couette and Poiseuille flow?
In Couette flow, one plate is moving with respect to the other plate, and that relative motion drives the shearing action in the fluid between the plates. In Poiseuille flow, the plates are both stationary and the flow is driven by an external pressure gradient.
What is Couette flow and Poiseuille flow?
Combined Couette / Poiseuille flow is the steady flow between two flat plates, a fixed distance apart, in which the plates move relative to each other and there is a pressure gradient parallel to the plates. It is useful to bear this flow in mind when considering boundary layers next.
How do you find the drag constant?
The drag coefficient Cd is equal to the drag D divided by the quantity: density r times half the velocity V squared times the reference area A. The drag coefficient then expresses the ratio of the drag force to the force produced by the dynamic pressure times the area.
How do you find drag?
The drag equation states that drag D is equal to the drag coefficient Cd times the density r times half of the velocity V squared times the reference area A. For given air conditions, shape, and inclination of the object, we must determine a value for Cd to determine drag.
What determines the force required to move a plate?
Experimentally, under conditions of laminar flow, the force required to move a plate at constant speed against the resistance of a fluid is proportional to the area of the plate and to the velocity gradient perpendicular to the plate.
What is the viscosity of a plate?
Experimentally, under conditions of laminar flow, the force required to move a plate at constant speed against the resistance of a fluid is proportional to the area of the plate and to the velocity gradient perpendicular to the plate. The constant of proportionality is called the viscosity. Table of common viscosities Viscosity of Gases
How do you determine the resistance to flow in a liquid?
The resistance to flowin a liquid can be characterized in terms of the viscosityof the fluid if the flow is smooth. In the case of a moving plate in a liquid, it is found that there is a layer or lamina which moves with the plate, and a layer which is essentially stationary if it is next to a stationary plate.
How do you calculate the power of a moving object?
If we plug in the definition of work W = F → ˙ s → and simplify it, using that the force is constant and in the same direction as the movement, it becomes: P = d W d t = d ( F → ˙ s →) d t = d ( F s) d t = F d s d t + s d F d t = F d s d t = F v. So in words: the power ist simply the product of force and speed.