What is viscous dissipation?

What is viscous dissipation?

Definition. The irreversible process by means of which the work done by a fluid on adjacent layers due to the action of shear forces is transformed into heat is defined as viscous dissipation.

What are the units for viscosity?

The unit of viscosity, accordingly, is newton-second per square metre, which is usually expressed as pascal-second in SI units.

What is the unit of viscous force?

Pascal seconds
What is Viscosity?

Unit of Viscosity
Si Unit Pascal seconds (Pa·s) or kg·m−1·s−1
CGS Unit Poise (P)
Unit of Kinematic Viscosity
Si Unit square meter per second or m2/s

What is dissipation fluid?

Dissipation is the process of converting mechanical energy of downward-flowing water into thermal and acoustical energy. Various devices are designed in stream beds to reduce the kinetic energy of flowing waters to reduce their erosive potential on banks and river bottoms.

What is dissipation rate?

Energy dissipation rate is the parameter to determine the amount of energy lost by the viscous forces in the turbulent flow. Different approaches are used to calculate the energy dissipation rate, depending on the type of restrictions the fluid passes through.

What is an example of energy dissipation?

Dissipation is a term that is often used to describe ways in which energy is wasted. Any energy that is not transferred to useful energy stores is said to be wasted because it is lost to the surroundings. Electrical cables warming up are a good example of this.

What are examples of dissipated energy?

for a radio or set of speakers, the electrical work is transferred into useful sound waves and infrared radiation is dissipated – ie wasted as heat energy. for a tumble dryer, the electrical work is transferred into useful internal (thermal) energy which helps to dry clothes – energy is dissipated by sound waves.

How is viscous dissipation related to heat transfer?

Couette flow with heat transfer. Rate of energy generation per unit volume as a result of viscous dissipation is given by3 The velocity distribution for this problem is given by Eq. (8.1-12) as The use of Eq. (9.3-71) in Eq. (9.3-70) gives the rate of energy generation per unit volume as The boundary conditions for the temperature, i.e.,

Which is the governing equation for viscous dissipation?

Dividing each term by WL Δ x and taking the limit as Δ x → 0 give Substitution of Eq. (9.3-75) into Eq. (9.3-78) gives the governing equation for temperature as in which both viscosity and thermal conductivity are assumed to be independent of temperature.

How is viscous dissipation related to net hydrodynamic force?

The viscous dissipation of energy in this film is strong enough to dominate the net hydrodynamic force. In such case the rate of approach of two fluid particles obeys the Reynolds formula, which describes the rate of thinning of a planar film between two solid discs [28,23]:

When is the driving force of viscous dissipation undefined?

When Br = 4, θb = 1 from Eq. (9.3-90) and, as a result of very high viscous dissipation, Tb becomes uniform at the value of To. Since the driving force, i.e., To − Tb, is zero, Nu o is undefined under these circumstances.