The influence of temperature gradient on the Strouhal–Reynolds number relationship for water and air

Vít, Tomáš; Ren, M Maosheng; Trávníček, Z.; Maršík, František; Rindt, Ccm Camilo

doi:10.1016/j.expthermflusci.2006.08.002

Cited by 22 publications

(6 citation statements)

References 28 publications

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“…They found that the Strouhal-Reynolds formula used for the prediction of vortex shedding behind an unheated cylinder is still applicable to heated cylinders by adopting the effective Reynolds number concept. More recently, Vít et al (2007) also confirmed that the concept of effective Reynolds number would be applicable for both air and water flows if the heated cylinder operates in the forced convection region. They also suggested that the empirical constant, C, should be 0.97 for water flows, whereas the constant was suggested by Wang et al (2000) to be 0.28 for air flows.…”

Section: The Strouhal Number Of the Wake Vortex Sheddingmentioning

confidence: 67%

Thermal effects on the wake of a heated circular cylinder operating in mixed convection regime

Koochesfahani

2011

J. Fluid Mech.

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The thermal effects on the wake flow behind a heated circular cylinder operating in the mixed convection regime were investigated experimentally in the present study. The experiments were conducted in a vertical water channel with the heated cylinder placed horizontally and the flow approaching the cylinder downwards. With such a flow arrangement, the direction of the thermally induced buoyancy force acting on the fluid surrounding the heated cylinder would be opposite to the approach flow. During the experiments, the temperature and Reynolds number of the approach flow were held constant. By adjusting the surface temperature of the heated cylinder, the corresponding Richardson number (Ri = Gr/Re 2 ) was varied between 0.0 (unheated) and 1.04, resulting in a change in the heat transfer process from forced convection to mixed convection. A novel flow diagnostic technique, molecular tagging velocimetry and thermometry (MTV&T), was used for qualitative flow visualization of thermally induced flow structures and quantitative, simultaneous measurements of flow velocity and temperature distributions in the wake of the heated cylinder. With increasing temperature of the heated cylinder (i.e. Richardson number), significant modifications of the wake flow pattern and wake vortex shedding process were clearly revealed. When the Richardson number was relatively small (Ri 0.31), the vortex shedding process in the wake of the heated cylinder was found to be quite similar to that of an unheated cylinder. As the Richardson number increased to ∼0.50, the wake vortex shedding process was found to be 'delayed', with the wake vortex structures beginning to shed much further downstream. As the Richardson number approached unity (Ri 0.72), instead of having 'Kármán' vortices shedding alternately at the two sides of the heated cylinder, concurrent shedding of smaller vortex structures was observed in the near wake of the heated cylinder. The smaller vortex structures were found to behave more like 'Kelvin-Helmholtz' vortices than 'Kármán' vortices, and adjacent small vortices would merge to form larger vortex structures further downstream. It was also found that the shedding frequency of the wake vortex structures decreased with increasing Richardson number. The wake closure length and the drag coefficient of the heated cylinder were found initially to decrease slightly when the Richardson number was relatively small (Ri < 0.31), and then to increase monotonically with increasing Richardson number as the Richardson number became relatively large (Ri > 0.31). The † Email address for correspondence: huhui@iastate.edu 236 H. Hu and M. M. Koochesfahani average Nusselt number (Nu) of the heated cylinder was found to decrease almost linearly with increasing Richardson number.

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Section: The Strouhal Number Of the Wake Vortex Sheddingmentioning

confidence: 67%

Thermal effects on the wake of a heated circular cylinder operating in mixed convection regime

Koochesfahani

2011

J. Fluid Mech.

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“…The flow parameters were chosen to correspond with those of [5], where an influence of heating to the Strouhal number was studied experimentally. The Strouhal number obtained from our computation in comparison to the values from the experiment then provides a basic information about the relevance of the computational results.…”

Section: Introductionmentioning

confidence: 99%

On computations of temperature dependent incompressible flows by high order methods

Pech

2016

EPJ Web of Conferences

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Abstract. Parallel vortex shedding from the heated cylinder as dependent on the cylinder temperature is investigated in numerical simulation. The computational scheme for the system of the incompressible Navier-Stokes equations coupled with the heat equation is presented. The scheme is based on the mixed implicit-explicit solver of the third order and the spectral element method for the spatial approximation. The results are compared with the experiments for flow of air and water. The Strouhal-Prandtl-Reynolds relationship and evolution of the separation angle as dependence on the temperature is the final result of the computations.

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“…(2) (or the T eff and Re eff concept) not only for the laminar regime but also for the transitional wake regime. Recently, the experimental study by Vít et al [15] verified once more this concept and made a good demonstration to extend this concept further for water as the working fluid (understandably, the constant in Eq. (1) cannot be the same for different fluids).…”

Section: Introductionmentioning

confidence: 82%

On the effective temperature and Reynolds number concept for a heated circular cylinder: commentary of the article by Baranyi et al.

Trávníček

Wang

2011

J Mech Sci Technol

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The influence of temperature gradient on the Strouhal–Reynolds number relationship for water and air

Cited by 22 publications

References 28 publications

Thermal effects on the wake of a heated circular cylinder operating in mixed convection regime

Thermal effects on the wake of a heated circular cylinder operating in mixed convection regime

On computations of temperature dependent incompressible flows by high order methods

On the effective temperature and Reynolds number concept for a heated circular cylinder: commentary of the article by Baranyi et al.

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