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Settling velocity

The terminal velocity of a particle which is falling in the viscous fluid under its own weight due to gravity.
Generally, for small particles (laminar ... more

Rouse Number

The Rouse number (P or Z) is a non-dimensional number in fluid dynamics which is used to define a concentration profile of suspended sediment and which ... more

Particle diameter (phi scale)

Particle size, also called grain size, refers to the diameter of individual grains of sediment, or the lithified particles in clastic rocks.
Size ... more

Area-based particle size

Particle size is a notion introduced for comparing dimensions of solid particles (flecks), liquid particles (droplets), or gaseous particles (bubbles).
... more

Shields Parameter

The Shields parameter, also called the Shields criterion or Shields number, is a nondimensional number used to calculate the initiation of motion of ... more

Bagnold number

he Bagnold number (Ba) is the ratio of grain collision stresses to viscous fluid stresses in a granular flow with interstitial Newtonian fluid, first ... more

Porosity

The volume of the voids of a soil over the total volume of the sample defines the porosity of a soil. Used in geology, hydrogeology, soil science, and ... more

Worksheet 300

Calculate the Reynolds number N′R for a ball with a 7.40-cm diameter thrown at 40.0 m/s.

Strategy

We can use the Reynolds number equation calculate N’R , since all values in it are either given or can be found in tables of density and viscosity.

Solution

We first find the kinematic viscosity values:

Kinematic Viscosity

Substituting values into the equation for N’R yields:

Reynolds number

Discussion

This value is sufficiently high to imply a turbulent wake. Most large objects, such as airplanes and sailboats, create significant turbulence as they move. As noted before, the Bernoulli principle gives only qualitatively-correct results in such situations.

Reference : OpenStax College,College Physics. OpenStax College. 21 June 2012.
http://openstaxcollege.org/textbooks/college-physics
Creative Commons License : http://creativecommons.org/licenses/by/3.0/

Rayleigh number (for the mushy zone of a solidifying alloy - related to isotherm speed)

In fluid mechanics, the Rayleigh number (Ra) for a fluid is a dimensionless number associated with buoyancy-driven flow, also known as free convection or ... more

Rayleigh number (for the mushy zone of a solidifying alloy)

In fluid mechanics, the Rayleigh number (Ra) for a fluid is a dimensionless number associated with buoyancy-driven flow, also known as free convection or ... more

Reynolds number

In fluid mechanics, the Reynolds number (Re) is a dimensionless quantity that is used to help predict similar flow patterns in different fluid flow ... more

Roshko number

In fluid mechanics, the Roshko number is a dimensionless number describing oscillating flow mechanisms.It is related to the Strouhal number and the ... more

Rayleigh Number

In fluid mechanics, the Rayleigh number (Ra) for a fluid is a dimensionless number associated with buoyancy driven flow (also known as free convection or ... more

Rayleigh number (for a uniform wall heating flux)

In fluid mechanics, the Rayleigh number (Ra) for a fluid is a dimensionless number associated with buoyancy-driven flow, also known as free convection or ... more

Boundary layer thickness (For laminar boundary layers over a flat plate)

The boundary layer thickness is the distance across a boundary layer from the wall to a point where the flow velocity has essentially reached (99%)the ... more

Drag coefficient for a spherical object in creeping flow

In fluid dynamics, the drag coefficient is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment, ... more

Porosity (density related)

Porosity or void fraction is a measure of the void (i.e., “empty”) spaces in a material, and is a fraction of the volume of voids over the ... more

Reynolds number (for motion of an object in a viscous fluid)

In fluid mechanics, the Reynolds number is used to help predict if flow will be laminar or turbulent. We know that the flow around a smooth, streamlined ... more

Friction Loss (laminar flow)

In fluid flow, friction loss (or skin friction) is the loss of pressure or “head” that occurs in pipe or duct flow due to the effect of the fluid’s ... more

Prandtl number

The Prandtl number (Pr) or Prandtl group is a dimensionless number, named after the German physicist Ludwig Prandtl, defined as the ratio of momentum ... more

Knudsen number (Relationship to Mach and Reynolds numbers in gases)

The Knudsen number (Kn) is a dimensionless number defined as the ratio of the molecular mean free path length to a representative physical length scale. ... more

Péclet number (for mass transfer)

The Péclet number (Pe) is a class of dimensionless numbers relevant in the study of transport phenomena in a continuum. It is named after the French ... more

Reynolds number (for a flow in a tube)

In fluid mechanics, the Reynolds number is used to help predict if flow will be laminar or turbulent. We know that flow in a very smooth tube, streamlined ... more

Taylor Number

In fluid dynamics, the Taylor number (Ta) is a dimensionless quantity that characterizes the importance of centrifugal “forces” or so-called ... more

Rayleigh number (for geophysical applications)

In fluid mechanics, the Rayleigh number (Ra) for a fluid is a dimensionless number associated with buoyancy-driven flow, also known as free convection or ... more

Kinematic Viscosity

Viscosity is a property arising from collisions between neighboring particles in a fluid that are moving at different velocities. When the fluid is forced ... more

Film temperature

In heat transfer and fluid dynamics, the film temperature is an approximation to the temperature of a fluid inside a convection boundary layer. It is ... more

Effective diffusivity in porous media

A porous medium (or a porous material) is a material containing pores (voids). The skeletal portion of the material is often called the ... more

Rayleigh number (related to Grashof and Prandtl number)

In fluid mechanics, the Rayleigh number (Ra) for a fluid is a dimensionless number associated with buoyancy-driven flow, also known as free convection or ... more

Reynolds number - Flow in a pipe with mass flow rate

For flow in a pipe or tube, the Reynolds number is generally defined as presented here.

For shapes such as squares, rectangular or annular ducts ... more

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