Séminaire D2 : Impinging jet flow and hydraulic jump on a rotating disk


Nom: 
Roger Khayat, Dept. Mechanical & Materials Engineering, Univ. of Western Ontario
Lieu Evenemement: 
Salle 175/177, bâtiment H2, SP2MI
Date: 
Jeudi, 8 Mars, 2018 - 14:00
Description: 

Attention: Ce séminaire sera donné en français

 

Abstract:

 

The free-surface flow formed by a circular jet impinging on a rotating disk is analyzed theoretically. The study explores the effects of rotation and inertia on the thin-film flow. Both boundary-layer height and film thickness are found to diminish with rotation speed. A maximum film thickness develops in the supercritical region, which reflects the competition between the convective and centrifugal effects. Unlike the flow on a stationary disk, an increase in the wall shear stress along the radial direction is predicted, at a rate that strengthens with rotating speed. Our results corroborate well existing measurements (Ozar et al. 2003). The location and height of the hydraulic jump are determined subject to the value of the thickness at the edge of the disk, which is established first for a stationary disk based on the capillary length, and then for a rotating disk using existing analyses and measurements in spin coating. The case of a stationary disk is revisited in an effort to predict the location and height of the jump uniquely. Despite the prolific number of studies since the seminal work of Watson (1964), this remains an outstanding issue in the literature (see, for instance, Duchesne et al. 2014). In this study, the formulated value of the film height at the edge of the disk seems to give excellent agreement against existing measurements (Dressaire et al. 2010) for a jet at moderately high flow rate or low viscosity where the jump structure is well identifiable in reality. The current study (Yunpeng & Khayat 2018) is the latest in a series of works where we previously explored non-Newtonian effects (Zhao & Khayat 2008) and the influence of slip (Khayat 2016) on the formation of hydraulic jump, which I will briefly highlight in my talk.

 

Dressaire, E., Courbin, L., Crest, J. & Stone H. A. 2010 Inertia dominated thin-film flows over microdecorated surfaces. Phys. Fluids 22,073602-07

 

Duchesne, A., Lebon, L. & Limat, L. 2014 Constant Froude number in a circular hydraulic jump and its implication on the jump radius selection. Europhys. Lett. 107, 54002.

 

Khayat, R. E. 2016 Impinging planar jet flow and hydraulic jump on a horizontal surface with slip.  J. Fluid Mech. 808, 258-289.

 

Ozar, B., Cetegen, B. M. & Faghri, A. 2003 Experiments on the flow of a thin liquid film over a horizontal stationary and rotating disk surface. Experiments in Fluids 34, 556–565.

 

Wang, Y. & Khayat, R.E. 2018 Impinging jet flow and hydraulic jump on a rotating disk. J. Fluid Mech. (in press).

 

Watson, E. 1964 The spread of a liquid jet over a horizontal plane. J. Fluid Mech. 20, 481-499.

 

Zhao, J. & Khayat, R.E. 2008 Spread of a non-Newtonian liquid jet over a horizontal plate. J. Fluid Mech. 613, 411-443.

Departement: 
D2







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