How are Stoke numbers calculated?
How are Stoke numbers calculated?
The gas characteristic time τc in the Stokes number definition has been determined based on the characteristic length (Lc) and the characteristic velocity (Vc) of the system under investigation, that is τc = Lc/Vc.
What is Stokes flow equation?
Navier-Stokes equation, in fluid mechanics, a partial differential equation that describes the flow of incompressible fluids. The equation is a generalization of the equation devised by Swiss mathematician Leonhard Euler in the 18th century to describe the flow of incompressible and frictionless fluids.
What is Stokeslet?
In the case of incompressible fluid motions at low Reynolds numbers, this singularity solution is known as the stokeslet. To introduce the stokeslet, we consider a rigid particle moving slowly in a viscous, incompressible fluid. The particle induces a fluid velocity whose magnitude decreases slowly with distance.
What is a Stokes particle?
In experimental fluid dynamics, the Stokes number is a measure of flow tracer fidelity in particle image velocimetry (PIV) experiments where very small particles are entrained in turbulent flows and optically observed to determine the speed and direction of fluid movement (also known as the velocity field of the fluid) …
What Reynolds number is Stokes?
Stokes law has been derived in the limit of vanishing Reynolds number (20-12), and is empirically valid for Re ≲ 1.
How is Reynolds number defined as?
The Reynolds number (NRe) is defined as the ratio of fluid momentum force to viscous shear force.
Is Stokes flow irrotational?
Slender-body theory. Slender-body theory in Stokes flow is a simple approximate method of determining the irrotational flow field around bodies whose length is large compared with their width.
What is the RE for creeping or Stokes flow?
The terminologies creeping flow, Stokes flow, or low Reynolds number hydrodynamics are used synonymously to refer to flows in which inertia is negligible compared to viscous and pressure forces. The formal requirement is that the Reynolds number be small: Re ≪ 1.
How do you calculate Stokes diameter?
Stokes diameter is the diameter of a sphere that has the same density and settling velocity as the particle. Aerodynamic diameter is the diameter of the unit density sphere that has the same settling velocity as the particle. – V ts = 0.003 x SG x d2 at NTP. – This equation gives V ts in cm/sec using d in microns.
What is capillary number in reservoir?
The capillary number indicates the magnitude of viscous forces, represented by fluid viscosity multiplied by its velocity, in relation to forces due to surface or interfacial tension.
Is Stokes flow laminar?
Stokes flow, also named creeping flow or creeping motion, is a type of fluid flow where advective inertial forces are small compared with viscous forces. This is a type of laminar flow, where streamlines are parallel to each other as shown in Figure 1 and the Reynolds number, Re<<1 [1,2].
Who discovered Reynolds number?
scientist Osborne Reynolds
In 1883, Irish scientist Osborne Reynolds discovered the dimensionless number that predicts fluid flow based on static and dynamic properties such as velocity, density, dynamic viscosity and characteristics of the fluid^2.
What is the formula for the Stokes number?
The Stokes number is the ratio of the particle’s momentum response time to the flow-field time scale: St = ρ p D p 2 / 18 μ D 0 / U 0. By definition, a larger Stokes number represents a larger or heavier particle, and a smaller or lighter particle has a smaller Stokes number.
What does a smaller Stokes number mean?
By definition, a larger Stokes number represents a larger or heavier particle, and a smaller or lighter particle has a smaller Stokes number. Three different Stokes numbers, 0.1, 1, and 10, were simulated with the same density, ρ p = 10 3, in this research.
What is wrong with the conventional Stokes number?
The conventional Stokes number will significantly underestimate the drag force for large particle free-stream Reynolds numbers. Thus overestimating the tendency for particles to depart from the fluid flow direction. This will lead to errors in subsequent calculations or experimental comparisons.
What is the Stokes number in fluid dynamics?
Stokes number. In experimental fluid dynamics, the Stokes number is a measure of flow tracer fidelity in particle image velocimetry (PIV) experiments where very small particles are entrained in turbulent flows and optically observed to determine the speed and direction of fluid movement (also known as the velocity field of the fluid).
