AnswersDriveThe Reynolds number is an important parameter in Transport Phenomena. It is used extensively in many calculations dealing with fluid flow, mass transfer and heat transfer. It is the ratio of the inertial forces to the viscous forces and depends on a characteristic length, velocity, density and viscosity of the fluid.
What does the Reynolds number tell us?
In fluid mechanics, the Reynolds number (Re) is a dimensionless number that gives a measure of the ratio of inertial forces to viscous forces and consequently quantifies the relative importance of these two types of forces for given flow conditions.
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What do you mean by steady flow?
Definition of steady flow. : a flow in which the velocity of the fluid at a particular fixed point does not change with time — called also stationary flow; compare uniform flow.
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What do you mean by turbulent flow?
Turbulent flow, type of fluid (gas or liquid) flow in which the fluid undergoes irregular fluctuations, or mixing, in contrast to laminar flow, in which the fluid moves in smooth paths or layers. In turbulent flow the speed of the fluid at a point is continuously undergoing changes in both magnitude and direction.
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What is the definition of Stokes law?
the law that the force that retards a sphere moving through a viscous fluid is directly proportional to the velocity of the sphere, the radius of the sphere, and the viscosity of the fluid. the law that the frequency of luminescence induced by radiation is usually less than the frequency of the radiation.
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What is the Venturimeter?
Venturimeter is the most widely used device to measure the discharge through the pipe. A venturi is a converging-Diverging nozzle of circular cross-section.
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What is the characteristic length?
In physics, a characteristic length is an important dimension that defines the scale of a physical system. Often, such a length is used as an input to a formula in order to predict some characteristics of the system. Examples: Reynolds Number. Biot number.
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What is the Nusselt number?
In heat transfer at a boundary (surface) within a fluid, the Nusselt number (Nu) is the ratio of convective to conductive heat transfer across (normal to) the boundary. In this context, convection includes both advection and diffusion.
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What is the Moody chart?
In engineering, the Moody chart or Moody diagram is a graph in non-dimensional form that relates the Darcy-Weisbach friction factor fD, Reynolds number Re, and relative roughness for fully developed flow in a circular pipe. It can be used to predict pressure drop or flow rate down such a pipe.
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What is the Weber number?
The Weber Number is a dimensionless value useful for analyzing fluid flows where there is an interface between two different fluids. The Weber Number is the ratio between the inertial force and the surface tension force and the Weber number indicates whether the kinetic or the surface tension energy is dominant.
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Why do we need Nusselt number?
The physical interpretation of Nusselt number is the enhancement of heat transfer due to convection over conduction alone. With Nu >1, the fluid motion enhances heat transfer by advection. The Nusselt number is of paramount importance because it contains the heat transfer coefficient information.
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What is the coefficient of drag?
The drag coefficient is a common measure in automotive design as it pertains to aerodynamics. Drag is a force that acts parallel and in the same direction as the airflow. The drag coefficient of an automobile impacts the way the automobile passes through the surrounding air.
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What is meant by viscous forces?
A measure of a fluid's resistance to flow. Viscous forces in a fluid are proportional to the rate at which the fluid velocity is changing in space; the proportionality constant is the viscosity.
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What is the Grashof number?
The Grashof number (Gr) is a dimensionless number in fluid dynamics and heat transfer which approximates the ratio of the buoyancy to viscous force acting on a fluid. It frequently arises in the study of situations involving natural convection and is analogous to the Reynolds number.
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What is the viscosity of water?
The dynamic viscosity of water is 8.90 × 10−4 Pa. · s or 8.90 × 10−3 dyn. · s/cm2 or 0.890 cP at about 25 °C. Water has a viscosity of 0.0091 poise at 25 °C, or 1 centipoise at 20 °C. As a function of temperature T (K): (Pa.
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What is inertia force in fluid?
As in classical mechanics, a force that can counteract or counterbalance this inertial force is the force of friction (shear stress).In the case of fluid flow, this is represented by Newtons law, τ x = μ d v d y . This is only dependent on the viscosity and gradient of velocity.
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What is the coefficient of discharge?
In a nozzle or other constriction, the discharge coefficient (also known as coefficient of discharge) is the ratio of the actual discharge to the theoretical discharge, i.e., the ratio of the mass flow rate at the discharge end of the nozzle to that of an ideal nozzle which expands an identical working fluid from the
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What is a dimensionless number?
In dimensional analysis, a dimensionless quantity (or more precisely, a quantity with the dimensions of 1) is a quantity without any physical units and thus a pure number. Such a number is typically defined as a product or ratio of quantities which do have units, in such a way that all the units cancel out.
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What is the formula for Reynolds number?
Reynolds number is used to check whether the flow is laminar or turbulent. It is denoted by Re. This number got by comparing inertial force with Viscous force. Reynolds number formula is used in the problems to find the Velocity (V), density ( ), Viscosity ( ) and diameter (L) of the fluid. It is dimensionless.
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What is the purpose of a Venturi meter?
Venturi meters are flow measurement instruments which use a converging section of pipe to give an increase in the flow velocity and a corresponding pressure drop from which the flowrate can be deduced. They have been in common use for many years, especially in the water supply industry.
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What is the ratio of the Reynolds number?
The Reynolds number (Re) is the ratio of inertial resistance to viscous resistance for a flowing fluid. The Reynolds number is a non-dimensional (unitless) factor governing resistance due to viscosity (among other things). Reynolds, Osborne."