Information about Graetz Number
In fluid dynamics, the Graetz number (Gz) is a dimensionless number that characterises laminar flow in a conduit. The number is defined as:
where
When used in connection with mass transfer the Prandtl number is replaced by the Schmidt number which expresses the ratio of the momentum diffusivity to the mass diffusivity.
The quantity is named after the physicist Leo Graetz.
where
- di is the internal diameter in round tubes or hydraulic diameter in arbitrary cross-section ducts
- L is the length
- Re is the Reynolds number and
- Pr is the Prandtl number.
When used in connection with mass transfer the Prandtl number is replaced by the Schmidt number which expresses the ratio of the momentum diffusivity to the mass diffusivity.
The quantity is named after the physicist Leo Graetz.
Fluid dynamics is the sub-discipline of fluid mechanics dealing with fluids (liquids and gases) in motion. It has several subdisciplines itself, including aerodynamics (the study of gases in motion) and hydrodynamics (the study of liquids in motion).
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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.
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In fluid mechanics, the Reynolds number is the ratio of inertial forces (vsρ) to viscous forces (μ/L) and consequently it quantifies the relative importance of these two types of forces for given flow conditions.
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The Prandtl number is a dimensionless number approximating the ratio of momentum diffusivity (viscosity) and thermal diffusivity. It is named after Ludwig Prandtl.
It is defined as:
where:
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It is defined as:
where:
- is the kinematic viscosity, ν =
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The Schmidt number is a dimensionless number defined as the ratio of momentum diffusivity (viscosity) and mass diffusivity, and is used to characterize fluid flows in which there are simultaneous momentum and mass diffusion convection processes. It was named after Ernst Schmidt.
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Leo Graetz (September 26, 1856 – November 12, 1941) was a German physicist. He was born in Breslau (Wrocław) as the son of the historian Heinrich Graetz.
Graetz was one of the first to investigate the propagation of electromagnetic energy.
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Graetz was one of the first to investigate the propagation of electromagnetic energy.
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