Hedstrom Number
Hedstrom number, abbreviated as He, a dimensionless number, is used in fluid dynamics to characterize the relative importance of viscous forces to inertial forces in a fluid flow. The Hedström number helps determine whether viscous effects or inertial effects dominate in a fluid flow. Its interpretation is similar to the Reynolds number, which is another dimensionless parameter used in fluid dynamics. The key differences between the Hedström number and the Reynolds number are the choice of characteristic velocity and the absence of density in the Hedström number.
Hedstrom number Interpretation
- $1 -$ It indicates that viscous forces dominate over inertial forces. In such cases, the fluid flow is typically characterized by laminar flow behavior, with smooth and ordered flow patterns.
- $1 -$ It suggests that inertial forces are dominant, and the fluid flow is more likely to be turbulent, with chaotic and irregular flow patterns.
The Hedstrom number is used primarily in the analysis of low speed, high viscosity flows where density variations are not significant. It is commonly employed in chemical engineering and fluid mechanics applications to understand and predict flow behavior, particularly in cases where the Reynolds number may not be the most appropriate parameter due to the absence of density information.
Hedstrom Number formula |
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\( He \;=\; \left(\rho\;d^2\right) \; \tau \;/\; \mu^2 \) | ||
Symbol | English | Metric |
\( He \) = Hedstrom number | \(dimensionless\) | |
\( \rho \) (Greek symbol rho) = mass density of fluid | \(lbm\;/\;ft^3\) | \(kg\;/\;m^3\) |
\( d \) = pipe inside diameter | \(in^2\) | \(mm^2\) |
\( \tau \) (Greek symbol tau) = yield point of fluid | \(in\) | \(mm\) |
\( \mu \) (Greek symbol mu) = dynamic viscosity | \(lbf-sec\;/\;ft^2\) | \( Pa-s \) |
Tags: Fluid