Effects of longitudinal grooves on the Couette–Poiseuille flow

On the use of transpiration patterns for reduction of pressure losses

“…It is known that short wavelength longitudinal grooves (riblets) can reduce drag by forcing the stream to lift above the grooves (Walsh 1980, 1983). It is also known that long wavelength longitudinal grooves can lead to drag reduction through changes in the distribution of the bulk flow (Szumbarski, Blonski & Kowalewski 2011, Moradi & Floryan 2013; Mohammadi & Floryan 2013 a , 2014, 2015; Mohammadi, Moradi & Floryan 2015, Chen et al. 2016; DeGroot, Wang & Floryan 2016; Raayai-Ardakani & McKinley 2017; Yadav, Gepner & Szumbarski 2017, 2018).…”

Spectrally-accurate algorithm for the analysis of flows in two-dimensional vibrating channels

“…The efficiency has been increased by an order of magnitude through the development of specialized solvers which account for the special structure of the coefficient matrix [38,39]. The method has been used to identify the laminar drag-reducing grooves [16][17][18][19][20] and to study the effects of various grooves on the flow stability [40][41][42][43][44][45][46]. This work is focused on the development of an efficient algorithm suitable for the analysis of changes in the pressure gradient required to drive a specified flow rate through a vibrating channel.…”

“…An analytical mapping of the irregular physical domain to a rectangular computational domain can help improve the accuracy at the cost of increased complexity of the field equations [13,14]. However, such mappings are available only for a limited class of geometries [1] and reconstruction of the coefficient matrix during each time step can add to the overall computational cost by a substantial margin [14][15][16][17][18][19][20].…”

The role of vibrations for reducing the resistance in the relative movement of parallel plates

“…Possible routes to secondary states and to turbulence have been described by Deguchi & Nagata (2011) and Tillmark & Alfredsson (1992). It is known that bypass transition can be initiated by wall transpiration (Floryan 2003), by adding transverse ribs (Floryan 2002) or by using grooves (Mohammadi & Floryan 2014).…”