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Stanton Number
The Stanton number (), is a dimensionless number that measures the ratio of heat transferred into a fluid to the thermal capacity of fluid. The Stanton number is named after Thomas Stanton (engineer) (1865–1931). It is used to characterize heat transfer in forced convection flows. Formula \mathrm = \frac = \frac where *''h'' = convection heat transfer coefficient *''G'' = mass flux of the fluid * ''ρ'' = density of the fluid *''cp'' = specific heat of the fluid *''u'' = velocity of the fluid It can also be represented in terms of the fluid's Nusselt, Reynolds, and Prandtl numbers: :\mathrm = \frac where * Nu is the Nusselt number; * Re is the Reynolds number; * Pr is the Prandtl number. The Stanton number arises in the consideration of the geometric similarity of the momentum boundary layer and the thermal boundary layer, where it can be used to express a relationship between the shear force at the wall (due to viscous drag) and the total heat transfer at the wall (due ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimensionless Number
Dimensionless quantities, or quantities of dimension one, are quantities implicitly defined in a manner that prevents their aggregation into unit of measurement, units of measurement. ISBN 978-92-822-2272-0. Typically expressed as ratios that align with another system, these quantities do not necessitate explicitly defined Unit of measurement, units. For instance, alcohol by volume (ABV) represents a volumetric ratio; its value remains independent of the specific Unit of volume, units of volume used, such as in milliliters per milliliter (mL/mL). The 1, number one is recognized as a dimensionless Base unit of measurement, base quantity. Radians serve as dimensionless units for Angle, angular measurements, derived from the universal ratio of 2π times the radius of a circle being equal to its circumference. Dimensionless quantities play a crucial role serving as parameters in differential equations in various technical disciplines. In calculus, concepts like the unitless ratios ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boundary Layer
In physics and fluid mechanics, a boundary layer is the thin layer of fluid in the immediate vicinity of a Boundary (thermodynamic), bounding surface formed by the fluid flowing along the surface. The fluid's interaction with the wall induces a No-slip condition, no-slip boundary condition (zero velocity at the wall). The flow velocity then monotonically increases above the surface until it returns to the bulk flow velocity. The thin layer consisting of fluid whose velocity has not yet returned to the bulk flow velocity is called the velocity boundary layer. The air next to a human is heated, resulting in gravity-induced convective airflow, which results in both a velocity and thermal boundary layer. A breeze disrupts the boundary layer, and hair and clothing protect it, making the human feel cooler or warmer. On an aircraft wing, the velocity boundary layer is the part of the flow close to the wing, where viscosity, viscous forces distort the surrounding non-viscous flow. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eponymous Numbers
This is a list of physical and mathematical constants named after people. Eponymous constants and their influence on scientific citations have been discussed in the literature. Endre Száva-Kováts. "Journal of Information Science;" (1994); 20:55 * – * Archimedes' constant (, pi) � ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimensionless Numbers Of Thermodynamics
Dimensionless quantities, or quantities of dimension one, are quantities implicitly defined in a manner that prevents their aggregation into units of measurement. ISBN 978-92-822-2272-0. Typically expressed as ratios that align with another system, these quantities do not necessitate explicitly defined units. For instance, alcohol by volume (ABV) represents a volumetric ratio; its value remains independent of the specific units of volume used, such as in milliliters per milliliter (mL/mL). The number one is recognized as a dimensionless base quantity. Radians serve as dimensionless units for angular measurements, derived from the universal ratio of 2π times the radius of a circle being equal to its circumference. Dimensionless quantities play a crucial role serving as parameters in differential equations in various technical disciplines. In calculus, concepts like the unitless ratios in limits or derivatives often involve dimensionless quantities. In differential geom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimensionless Numbers Of Fluid Mechanics
Dimensionless quantities, or quantities of dimension one, are quantities implicitly defined in a manner that prevents their aggregation into unit of measurement, units of measurement. ISBN 978-92-822-2272-0. Typically expressed as ratios that align with another system, these quantities do not necessitate explicitly defined Unit of measurement, units. For instance, alcohol by volume (ABV) represents a volumetric ratio; its value remains independent of the specific Unit of volume, units of volume used, such as in milliliters per milliliter (mL/mL). The 1, number one is recognized as a dimensionless Base unit of measurement, base quantity. Radians serve as dimensionless units for Angle, angular measurements, derived from the universal ratio of 2π times the radius of a circle being equal to its circumference. Dimensionless quantities play a crucial role serving as parameters in differential equations in various technical disciplines. In calculus, concepts like the unitless ratios ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strouhal Number
In dimensional analysis, the Strouhal number (St, or sometimes Sr to avoid the conflict with the Stanton number) is a dimensionless number describing oscillating flow mechanisms. The parameter is named after Vincenc Strouhal, a Czech physicist who experimented in 1878 with wires experiencing vortex shedding and singing in the wind. The Strouhal number is an integral part of the fundamentals of fluid mechanics. The Strouhal number is often given as : \text = \frac, where ''f'' is the frequency of vortex shedding in Hertz, ''L'' is the characteristic length (for example, hydraulic diameter or the airfoil thickness) and ''U'' is the flow velocity. In certain cases, like heaving (plunging) flight, this characteristic length is the amplitude of oscillation. This selection of characteristic length can be used to present a distinction between Strouhal number and reduced frequency: : \text = \frac, where ''k'' is the reduced frequency, and ''A'' is amplitude of the heaving oscilla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schmidt Number
In fluid dynamics, the Schmidt number (denoted ) of a fluid is a dimensionless number defined as the ratio of momentum diffusivity (kinematic viscosity) and mass diffusivity, and it is used to characterize fluid flows in which there are simultaneous momentum and mass diffusion convection processes. It was named after German engineer Ernst Heinrich Wilhelm Schmidt (1892–1975). The Schmidt number is the ratio of the shear component for diffusivity (viscosity divided by density) to the diffusivity for mass transfer . It physically relates the relative thickness of the hydrodynamic layer and mass-transfer boundary layer. It is defined as: :\mathrm = \frac = \frac = \frac = \frac where (in SI units): * \nu = \tfrac \mu \rho is the kinematic viscosity (m2/s) * is the mass diffusivity (m2/s). * is the dynamic viscosity of the fluid (Pa·s = N·s/m2 = kg/m·s) * is the density of the fluid (kg/m3) * is the Peclet Number * is the Reynolds Number. The heat transfer analog of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sherwood Number
The Sherwood number (Sh) (also called the mass transfer Nusselt number) is a dimensionless number used in mass-transfer operation. It represents the ratio of the total mass transfer rate (convection + diffusion) to the rate of diffusive mass transport, and is named in honor of Thomas Kilgore Sherwood. It is defined as follows :\mathrm = \frac = \frac where * ''L'' is a characteristic length (m) * ''D'' is mass diffusivity (m2 s−1) * ''h'' is the convective mass transfer film coefficient (m s−1) Using dimensional analysis, it can also be further defined as a function of the Reynolds and Schmidt numbers: :\mathrm = f(\mathrm, \mathrm) For example, for a single sphere it can be expressed as : :\mathrm = \mathrm_0 + C\, \mathrm^\, \mathrm^ where \mathrm_0 is the Sherwood number due only to natural convection and not forced convection. A more specific correlation is the Froessling equation: :\mathrm = 2 + 0.552\, \mathrm^\, \mathrm^ This form is applicable to molecula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal Diffusivity
In thermodynamics, thermal diffusivity is the thermal conductivity divided by density and specific heat capacity at constant pressure. It is a measure of the rate of heat transfer inside a material and has SI, SI units of m2/s. It is an intensive property. Thermal diffusivity is usually denoted by lowercase alpha (), but , , (kappa), , , D_T are also used. The formula is \alpha = \frac, where : is thermal conductivity (W/(m·K)), : is specific heat capacity (J/(kg·K)), : is density (kg/m3). Together, can be considered the volumetric heat capacity (J/(m3·K)). Thermal diffusivity is a positive coefficient in the heat equation: \frac = \alpha \nabla^2 T. One way to view thermal diffusivity is as the ratio of the time derivative of temperature to its Second derivative#Generalization to higher dimensions, curvature, quantifying the rate at which temperature concavity is "smoothed out". In a substance with high thermal diffusivity, heat moves rapidly through it because the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viscosity
Viscosity is a measure of a fluid's rate-dependent drag (physics), resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for example, syrup has a higher viscosity than water. Viscosity is defined scientifically as a force multiplied by a time divided by an area. Thus its SI units are newton-seconds per metre squared, or pascal-seconds. Viscosity quantifies the internal friction, frictional force between adjacent layers of fluid that are in relative motion. For instance, when a viscous fluid is forced through a tube, it flows more quickly near the tube's center line than near its walls. Experiments show that some stress (physics), stress (such as a pressure difference between the two ends of the tube) is needed to sustain the flow. This is because a force is required to overcome the friction between the layers of the fluid which are in relative motion. For a tube ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shear Force
In solid mechanics, shearing forces are unaligned forces acting on one part of a Rigid body, body in a specific direction, and another part of the body in the opposite direction. When the forces are Collinearity, collinear (aligned with each other), they are called ''tension forces'' or ''compression forces''. Shear force can also be defined in terms of Plane (geometry), planes: "If a plane is passed through a body, a force acting along this plane is called a ''shear force'' or ''shearing force''." Force required to shear steel This section calculates the force required to cut a piece of material with a shearing action. The relevant information is the area of the material being sheared, i.e. the area across which the shearing action takes place, and the shear strength of the material. A round bar of steel is used as an example. The shear strength is calculated from the tensile strength using a factor which relates the two strengths. In this case 0.6 applies to the example steel, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 diffusivity to thermal diffusivity. The Prandtl number is given as:where: * \nu : momentum diffusivity ( kinematic viscosity), \nu = \mu/\rho, ( SI units: m2/s) * \alpha : thermal diffusivity, \alpha = k/(\rho c_p), (SI units: m2/s) * \mu : dynamic viscosity, (SI units: Pa s = N s/m2) * k : thermal conductivity, (SI units: W/(m·K)) * c_p : specific heat, (SI units: J/(kg·K)) * \rho : density, (SI units: kg/m3). Note that whereas the Reynolds number and Grashof number are subscripted with a scale variable, the Prandtl number contains no such length scale and is dependent only on the fluid and the fluid state. The Prandtl number is often found in property tables alongside other properties such as viscosity and thermal conductivity. The mass transfer analog of the Prandtl number is the Schmidt number and the ratio of the Pran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
