What is meant by characteristic length?

What is meant by characteristic length?

In computational mechanics, a characteristic length is defined to force localization of a stress softening constitutive equation. The length is associated with an integration point. For 2D analysis, it is calculated by taking the square root of the area.

What is characteristic length in heat transfer?

The characteristic length is commonly defined as the volume of the body divided by the surface area of the body, i.e. The surface area should include the top and bottom of the cylinder.

What is characteristic length of flow?

For pipe flow, the characteristic length is taken as D (diameter of pipe). For the free surface flow like channel flow, it is taken as hydraulic depth (R = A/P; A being flow depth and P being wetted perimeter). Thus, for free surface flow in a circular pipe, it is D/4 and y (water depth) for wide rectangular channel.

What is the characteristic length of a plate?

Characteristic Length For a flat rectangular plate, Lc is the length of the side parallel to the direction of flow. For a flat plate, L* is the area (of one side) of the plate divided by its perimeter.

What is characteristic length natural convection?

A characteristic length, defined by the volume, surface area, and a dimensionality parameter, is. proposed for internal natural convection. For geometries (such as bodies in enclosures) without simple. and/or fundamental characteristic lengths, heat transfer correlations using the proposed characteristic.

What is meant by Biot number?

The Biot number (Bi) is a dimensionless quantity used in heat transfer calculations. It is named after the eighteenth century French physicist Jean-Baptiste Biot (1774–1862), and gives a simple index of the ratio of the thermal resistances inside of a body and at the surface of a body.

What is the characteristic length of a sphere?

The characteristic length is commonly defined as the volume of the hollow sphere divided by the surface area of the hollow sphere. then, the characteristic length is its radius (the distance from the central adiabat to the solid-fluid or convection boundary).

What is RA in heat transfer?

Rayleigh number is a dimensionless number that represents the ratio of buoyancy and thermal diffusivity. It can be obtained by the following equation: Ra : Rayleigh number.

What is meant by Rayleigh number?

The Rayleigh number is defined as the product of the Grashof number, which describes the relationship between buoyancy and viscosity within a fluid, and the Prandtl number, which describes the relationship between momentum diffusivity and thermal diffusivity.

What is Rayleigh number?

Rayleigh number is a dimensionless number that represents the ratio of buoyancy and thermal diffusivity. Difference between solid surface temperature and free stream temperature can be used as the characteristic temperature difference.

What is lumped capacity?

Definition. The lumped thermal capacity model is the simplest transient heat conduction approach. In this model, the temperature of the solid body is a function of the time only, which means that the temperature is assumed to be spatially independent (uniform).

What are Biot and Fourier numbers?

Fourier number is also known as dimensionless time and have effect on temperature before the steady state achieved. Biot number arises when we use third kind of boundary condition (i.e convective heat transfer in presence of external fluid surface). Both have significant effect on temperature distribution.

What is steady temperature?

The term “steady-state temperature” is often used interchangeably with the idea of thermal equilibrium, but the two ideas are not the same. When a system is in thermal equilibrium with its surroundings, everything (system + surroundings) are at the same temperature.