Related Experiment Video
Updated: Apr 12, 2026
10:03
Uncoupling Coriolis Force and Rotating Buoyancy Effects on Full-Field Heat Transfer Properties of a Rotating Channel
Published on: October 5, 2018
8.7K
Energy transfer and dissipation in forced isotropic turbulence
W D McComb1, A Berera1, S R Yoffe2
1SUPA, School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, The King's Buildings, Edinburgh EH9 3JZ, United Kingdom.
Summary
A new model explains how turbulence dissipation changes with Reynolds number, showing it decays as a power law. This finding, supported by simulations, refines our understanding of fluid dynamics at high Reynolds numbers.
Area of Science:
- Fluid Dynamics
- Turbulence Theory
Background:
- The Reynolds-number dependence of turbulent dissipation is crucial for understanding fluid flows.
- Existing models often lack accuracy at high Reynolds numbers.
Purpose of the Study:
- To develop and validate a model for the dimensionless dissipation rate's dependence on the integral scale Reynolds number.
- To investigate the asymptotic behavior of dissipation at infinite Reynolds numbers.
Main Methods:
- Derivation of a model from the dimensionless Kármán-Howarth equation.
- Direct numerical simulations (DNS) of forced isotropic turbulence up to R(L)=5875.
- Fitting the model to DNS data to determine coefficients.
Main Results:
- The dimensionless dissipation rate C(ɛ) decays as a power law R(L)(n) with n=-1.000±0.009.
- The decay is attributed to the increase in the Taylor surrogate U(3)/L.
- Model fitting yielded C=18.9±1.3 and an asymptotic value C(ɛ,∞)=0.468±0.006.
Conclusions:
- The derived model accurately describes the Reynolds-number dependence of turbulent dissipation.
- The study provides an asymptotic value for dissipation at infinite Reynolds numbers.
- Findings enhance the understanding of turbulence physics in various flow regimes.
Related Concept Videos
01:16Energy Conservation and Bernoulli's Equation
11.2K
Applying the conservation of energy principle or the work-energy theorem to an incompressible, inviscid fluid in laminar, steady, irrotational flow leads to Bernoulli's equation. It states that the sum of the fluid pressure, potential, and kinetic energy per unit volume is constant along a streamline.
All the terms in the equation have the dimension of energy per unit volume. The kinetic energy per unit volume is called the kinetic energy density, and the potential energy per unit volume is...
All the terms in the equation have the dimension of energy per unit volume. The kinetic energy per unit volume is called the kinetic energy density, and the potential energy per unit volume is...
11.2K
01:14Conservation of Energy in Control Volume
1.2K
Consider a turbine operating under steady-flow conditions. The control volume is drawn around the turbine, with fluid entering at one point and exiting at another. The turbine extracts energy from the fluid, which performs mechanical work (shaft work).
For steady flow systems, the time derivative of the stored energy becomes zero since there is no energy accumulation within the control volume. This simplifies the energy equation to:
For steady flow systems, the time derivative of the stored energy becomes zero since there is no energy accumulation within the control volume. This simplifies the energy equation to:
1.2K
01:20Mechanisms of Heat Transfer II
5.4K
In convection, thermal energy is carried by the large-scale flow of matter. Ocean currents and large-scale atmospheric circulation, which result from the buoyancy of warm air and water, transfer hot air from the tropics toward the poles and cold air from the poles toward the tropics. The Earth’s rotation interacts with those flows, causing the observed eastward flow of air in the temperate zones. Convection dominates heat transfer by air, and the amount of available space for the airflow...
5.4K
00:59Bernoulli's Equation
17.7K
In the middle of the nineteenth century, it was observed that two trains passing each other at a high relative speed get pulled towards each other. The same occurs when two cars pass each other at a high relative speed. The reason is that the fluid pressure drops in the region where the fluid speeds up. As the air between the trains or the cars increases in speed, its pressure reduces. The pressure on the outer parts of the vehicles is still the atmospheric pressure, while the resultant...
17.7K
01:17Non-conservative Forces
10.3K
Non-conservative forces are dissipative forces such as friction or air resistance. These forces take energy away from a system as it progresses. Unlike conservative forces, non-conservative forces do not have potential energy associated with them. This is because the energy is lost to the system and cannot be turned into useful work later.
Also unlike their conservative counterparts, they are path-dependent; where the object starts and stops does matter. For example, a grinding wheel applies a...
Also unlike their conservative counterparts, they are path-dependent; where the object starts and stops does matter. For example, a grinding wheel applies a...
10.3K
01:24Reynolds Transport Theorem
2.1K
The Reynolds transport theorem provides a framework to relate the time rate of change of an extensive property within a system to that in a control volume, which is crucial for analyzing fluid dynamics. Extensive properties, such as mass, velocity, acceleration, temperature, and momentum, can be expressed in terms of the mass of a fluid portion. These properties are called extensive because they depend on the system's size, while intensive properties are their corresponding values per unit...
2.1K