Does viscosity vary with temperature for liquids and gases?

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SUMMARY

Viscosity varies significantly with temperature for both liquids and gases. For liquids, dynamic and kinematic viscosities are largely independent of pressure, with viscosity decreasing as temperature increases. In contrast, for gases, dynamic viscosity remains stable at low to moderate pressures, but kinematic viscosity is affected by pressure due to the gas density. As temperature rises, the viscosity of gases increases due to enhanced molecular collisions.

PREREQUISITES
  • Understanding of fluid dynamics concepts
  • Knowledge of viscosity definitions and types (dynamic and kinematic)
  • Familiarity with the effects of temperature on physical properties
  • Basic principles of gas laws and behavior under pressure
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  • Explore the impact of pressure on gas viscosity using the ideal gas law
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  • Investigate experimental methods for measuring viscosity at different temperatures
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Students and professionals in fluid mechanics, chemical engineering, and materials science who are interested in the behavior of fluids under varying temperature and pressure conditions.

hoomanya
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Hi,
I think I'm mixing things up... For a flow with low compressibility, I know density varies but does viscosity also vary? Does that depend on whether the flow is laminar or turbulent.
Thanks,
H
 
Engineering news on Phys.org
For liquids, both the dynamic and kinematic viscosities are practically independent of pressure, and any small variation with pressure is usually disregarded, except at extremely high pressures.

For gases, this is also the case for dynamic viscosity (at low to moderate pressures), but not for kinematic viscosity since the density of a gas is proportional to its pressure


Viscosity is due to the internal frictional force that develops between different
layers of fluids as they are forced to move relative to each other.

Viscosity is caused by the cohesive forces between the molecules in liquids and by
the molecular collisions in gases, and it varies greatly with temperature.

The viscosity of liquids decreases with temperature, whereas the viscosity of
gases increases with temperature
 

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