scholarly journals Experimental Study on the Mixing of High-Schmidt-Number Scalar in Regular/Fractal Grid Turbulence

2013 ◽  
Vol 79 (799) ◽  
pp. 304-316
Author(s):  
Koichi HOSHINO ◽  
Kouji NAGATA ◽  
Yasuhiko SAKAI ◽  
Hiroki SUZUKI ◽  
Ryota UKAI ◽  
...  
2010 ◽  
Vol 2010 (0) ◽  
pp. 85-86
Author(s):  
Ryota UKAI ◽  
Hiroki SUZUKI ◽  
Kouji NAGATA ◽  
Yasuhiko SAKAI ◽  
Osamu TERASHIMA

2010 ◽  
Vol T142 ◽  
pp. 014069 ◽  
Author(s):  
Hiroki Suzuki ◽  
Kouji Nagata ◽  
Yasuhiko Sakai ◽  
Ryota Ukai

Author(s):  
Hiroki Suzuki ◽  
Kouji Nagata ◽  
Yasuhiko Sakai ◽  
Ryota Ukai

Turbulent mixing of high-Schmidt-number passive scalar in shear-free grid turbulence is experimentally investigated using a water channel. The Reynolds number based on the mesh size of the grid and cross-sectionally averaged mean velocity is 2,500. Rhodamine B (fluorescent dye) was used as a high-Schmidt-number passive scalar. The Schmidt number is about 2,100. The time-resolved particle image velocimetry (PIV) and the planar laser induced fluorescence (PLIF) technique were used to measure instantaneous two-component velocities and nondimensional concentration. Our PLIF algorithm corrects the following errors: spatiotemporal variation of local excitation intensity due to an inhomogeneous concentration field along the light path, time variation of fluorescence quantum yield, and spatiotemporal variation of incident laser intensity. The results show that the vertical profile of mean scalar can be well approximated by the error function. In contrast, the profile of scalar variance in outer region of the mixing layer cannot be approximated by the Gaussian profile. In addition, the half width of mean scalar is larger than that of the scalar variance profile.


2021 ◽  
Vol 33 (7) ◽  
pp. 073106 ◽  
Author(s):  
N. Lauriello ◽  
J. Kondracki ◽  
A. Buffo ◽  
G. Boccardo ◽  
M. Bouaifi ◽  
...  

2016 ◽  
Vol 150 ◽  
pp. 74-84 ◽  
Author(s):  
Adrian Zenklusen ◽  
Saša Kenjereš ◽  
Philipp Rudolf von Rohr

2016 ◽  
Vol 790 ◽  
pp. 158-172 ◽  
Author(s):  
Amirhossein Arzani ◽  
Alberto M. Gambaruto ◽  
Guoning Chen ◽  
Shawn C. Shadden

The wall shear stress (WSS) vector field provides a signature for near-wall convective transport, and can be scaled to obtain a first-order approximation of the near-wall fluid velocity. The near-wall flow field governs mass transfer problems in convection-dominated open flows with high Schmidt number, in which case a flux at the wall will lead to a thin concentration boundary layer. Such near-wall transport is of particular interest in cardiovascular flows whereby haemodynamics can initiate and progress biological events at the vessel wall. In this study we consider mass transfer processes in pulsatile blood flow of abdominal aortic aneurysms resulting from complex WSS patterns. Specifically, the Lagrangian surface transport of a species released at the vessel wall was advected in forward and backward time based on the near-wall velocity field. Exposure time and residence time measures were defined to quantify accumulation of trajectories, as well as the time required to escape the near-wall domain. The effect of diffusion and normal velocity was investigated. The trajectories induced by the WSS vector field were observed to form attracting and repelling coherent structures that delineated species distribution inside the boundary layer consistent with exposure and residence time measures. The results indicate that Lagrangian WSS structures can provide a template for near-wall transport.


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