Inverse method for electrodiffusional diagnostics of flows

Rehimi, Ferid; Aloui, Fethi; Nasrallah, Sassi Ben; Doubliez, Louis; Legrand, Jack

doi:10.1016/j.ijheatmasstransfer.2005.10.008

Cited by 38 publications

(27 citation statements)

References 19 publications

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“…1 (Rehimi et al 2006) verified this method by numerical simulations. The wall shear stress is calculated from wall shear rate using the Newton law:…”

Section: The Polarographic Methodsmentioning

confidence: 69%

Experimental investigation of the wall shear stress and the vortex dynamics in a circular impinging jet

et al. 2012

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The wall shear stress and the vortex dynamics in a circular impinging jet are investigated experimentally for Re = 1,260 and 2,450. The wall shear stress is obtained at different radial locations from the stagnation point using the polarographic method. The velocity field is given from the time resolved particle image velocimetry (TR-PIV) technique in both the free jet region and near the wall in the impinging region. The distribution of the momentum thickness is also inspected from the jet exit toward the impinged wall. It is found that the wall shear stress is correlated with the large-scale vortex passing. Both the primary vortices and the secondary structures strongly affect the variation of the wall shear stress. The maximum mean wall shear stress is obtained just upstream from the secondary vortex generation where the primary structures impinge the wall. Spectral analysis and cross-correlations between the wall shear stress fluctuations show that the vortex passing influences the wall shear stress at different locations simultaneously. Analysis of cross-correlations between temporal fluctuations of the wall shear stress and the transverse vorticity brings out the role of different vortical structures on the wall shear stress distribution for the two Reynolds numbers.

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“…1 (Rehimi et al 2006) verified this method by numerical simulations. The wall shear stress is calculated from wall shear rate using the Newton law:…”

Section: The Polarographic Methodsmentioning

confidence: 69%

Experimental investigation of the wall shear stress and the vortex dynamics in a circular impinging jet

et al. 2012

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“…the diffusion sub-layer is small enough compared to the viscous sub-layer in which it is generally considered that the near wall velocity field has a linear profile (Funfschilling, 2001;Rehimi et al, 2006). In our case of study, the Schmidt number is equal to Sc ¼1195.…”

Section: Inverse Methods For the Determination Of The Wall Shear Ratesmentioning

confidence: 90%

“…Then Mao and Hanratty (1992) and Patankar (1980) used it to solve mass transfer problems. This method was well developed by Rehimi et al (2006) for known simulated solutions of the diffusion-convection equation. The concentration profile allowed the calculation of the instantaneous Sherwood number by integration of the equation using the Simpson method:…”

Section: Inverse Methods For the Determination Of The Wall Shear Ratesmentioning

confidence: 99%

“…Our present purpose is the application of the inverse method (Rehimi et al, 2006) for a well-controlled flow under the hypothesis of a neglecting isolated gap effect as a first step of the study of three-segment probe frequency response for the test of the robustness of the inverse method. illustrated that the primary data given by the three independent macroscopic fluxes of the three-segment probes can be converted into information about the kinematics of the flow around the probe, i.e.…”

Section: Inverse Methods For the Determination Of The Wall Shear Ratesmentioning

confidence: 99%

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Inverse method for the dynamical analysis of wall shear rates using three-segment probes in parallel plate rheometer

Berrich

Aloui

Legrand

2011

Chemical Engineering Science

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“…This relationship has been used by several authors in different flow configurations (Labraga et al 2002;Tihon et al 2003); they found it relevant in unsteady flow conditions, even when compared with the inverse method (Rehimi et al 2006).…”

Section: Sobolik's Correctionmentioning

confidence: 99%

Unsteady flows in milli- and microsystems: analysis of wall shear rate fluctuations

Huchet¹,

Legentilhomme

Legrand

et al. 2011

Exp Fluids

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To cite this version:Abstract The particular benefits of microfluidic systems, in terms of heat and mass transfer enhancement, require conducting local flow diagnostics, especially when unsteady properties of the microflow can play a critical role at the reaction interface, as currently observed in the fields of bioengineering and chemical engineering. The present paper focuses on unsteady confined flows within microsystems characterized by various geometries of crossing channels and exhibiting high surface-to-volume ratios. An experimental analysis of the signal measured at microsensors embedded to the wall of microsystems is discussed. In the objective of performing flow diagnostics, including regime identification and wall flow structure recognition, two methods for electrochemical signal processing are investigated and compared within an experimental network of crossing minichannels. One method is based on the use of a transfer function, while the other, the so-called Sobolik solution (Sobolik et al. in Coll Czech Chem Commun 52:913-928, 1987), consists of finding a direct solution to the mass balance equation. Sobolik's method has been selected given its ability to provide a description, over a wide range of Reynolds numbers (317 \ Re \ 3,535), for all wall shear rate fluctuations, as well as for the associated mixing scales in the power spectra density (PSD). This technique is then applied to flow within micromixers composed of two crossing microchannels in order to study highly unsteady and inhomogeneous microflows. The hydraulic diameters of the studied channels are 500 and 833 lm, respectively. Two flow patterns are investigated herein: the crossing-flow type and the impinging flow (or so called co-flow) for a Reynolds number range between 173 and 3,356. The PSD of wall shear rate fluctuations reveals various flow characteristics depending on the microchannel aspect ratio.

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Inverse method for electrodiffusional diagnostics of flows

Cited by 38 publications

References 19 publications

Experimental investigation of the wall shear stress and the vortex dynamics in a circular impinging jet

Experimental investigation of the wall shear stress and the vortex dynamics in a circular impinging jet

Inverse method for the dynamical analysis of wall shear rates using three-segment probes in parallel plate rheometer

Unsteady flows in milli- and microsystems: analysis of wall shear rate fluctuations

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