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Technical Brief

# A Note on Heat Transfer Enhancement in Laminar Impinging Flows With Shear Thinning Inelastic Fluids

[+] Author and Article Information
Ajay Chatterjee

Department of Mechanical Engineering,
Santa Clara University,
500 El Camino Real,
Santa Clara, CA 95053
e-mail: achatterjee@scu.edu

Drazen Fabris

Department of Mechanical Engineering,
Santa Clara University,
500 El Camino Real,
Santa Clara, CA 95053
e-mail: dfabris@scu.edu

1Corresponding author.

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF HEAT TRANSFER. Manuscript received October 1, 2015; final manuscript received April 7, 2016; published online May 3, 2016. Assoc. Editor: Zhixiong Guo.

J. Heat Transfer 138(8), 084503 (May 03, 2016) (4 pages) Paper No: HT-15-1630; doi: 10.1115/1.4033386 History: Received October 01, 2015; Revised April 07, 2016

## Abstract

A recent article presented axisymmetric numerical calculations showing substantial heat transfer enhancement in a laminar impinging flow with shear thinning inelastic fluids. This paper compares enhancement in planar and axisymmetric geometries and presents empirical dependencies correlating heat transfer rates to fluid rheology. The parametric correlation is expressed in the form $∼ ReGp$. ReG is a generalized Reynolds number based on the reference strain rate and fluid rheology, and it is larger than the Newtonian Reynolds number for the same mean nozzle velocity and flow geometry. The value of p > 0 is estimated from the numerical data for weak and strong shear thinning. Within the impinging zone spanning the nozzle cross section, the value of p is essentially similar for both geometries, but in the wall jet the planar flow shows a somewhat larger value. The total heat transfer rate in the planar wall jet may be two to ten times larger for a shear thinning fluid. This is because in shear thinning flow, the primary separation vortex is able to maintain the Nusselt number at a higher average value over a significantly longer length scale in the streamwise direction.

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## References

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## Figures

Fig. 1

Planar flow geometry and boundary conditions

Fig. 5

Total wall jet heat transfer rate in (a) axisymmetric and (b) planar flow

Fig. 4

Primary vortex length scaling versus ReG

Fig. 3

Average Nusselt number in impinging zone for (a) weak and (b) strong shear thinning

Fig. 2

Nusselt number comparisons

## Errata

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