- Title
- Characteristics of passive scalar within Kármán vortices
- Creator
- Chen, J. G.; Antonia, R. A.; Zhou, Y.; Zhou, T. M.
- Relation
- 21st Australasian Fluid Mechanics Conference 2018 (AFMC 2018). Proceedings of 21st Australasian Fluid Mechanics Conference 2018 (AFMC 2018) (Adelaide, SA 10 -13December, 2018)
- Publisher
- Australasian Fluid Mechanics Society
- Resource Type
- conference paper
- Date
- 2018
- Description
- This work focuses on the statistical properties of the temperature (passive scalar) field exclusively inside the Kármán vortex based on the phase-averaging data, which are intrinsically different from the conventionally averaged statistics that weight all regions of the flow equally. The vortices are generated by a circular cylinder, and the fluctuating flow velocity and temperature behind the cylinder are simultaneously measured in the plane of mean shear at x/d = 10 where x is the streamwise distance from the cylinder centre and d is the cylinder diameter. The Reynolds number based on d and the free-stream velocity is 2.5×103. Statistics of the temperature fluctuation θ and its streamwise derivative θ,1, including their probability density function, skewness and kurtosis inside the Kármán vortex are found to follow a Gaussian distribution, which is distinctly different from their conventional counterparts. Both the conditional correlation coefficient between θ and θ,21 and the conditional expectation of θ,21 indicate that the temperature field inside the Kármán vortex is free from the effect of the large-scale events outside the vortex, like the cold/warm temperature front along the diverging separatrix and the coherent strain in the saddle region, so that the small- and large-scale fluctuating temperatures inside the vortex are at best weakly coupled, which is the major reason for the almost Gaussian behavior of the statistics of the temperature field inside the Kármán vortex.
- Subject
- temperature fluctuation; density function; temperature field; karman vortex
- Identifier
- http://hdl.handle.net/1959.13/1481258
- Identifier
- uon:50689
- Identifier
- ISBN:9780646597843
- Language
- eng
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