SHEAR STRESS MEASUREMENTS AT THE SEA BOTTOM BY MEANS OF FERROFLUIDS
AbstractAn innovative measurement technique is proposed for investigating shear stress at sandy bottoms. This technique is based on the adoption of a ferrofluidic sensor and of an optical readout strategy. An experimental campaign is carried out for evaluating its performance. Experiments differ for the ferrofluidic sensor configuration (difference in the magnetic field) and for the bottom configurations (fixed bed or sandy bed). Calibration of the ferrofluidic sensor for the range of the investigated hydraulic condition and of the controlling magnetic field is presented. The ferrofluidic technique is promising when applied at sandy bottoms, as neither adhesion processes between sand grains and ferrofluid or influence of impacts of grains on the measurement are observed. In particular, the preliminary measure performed indicated that the ferrofluidic sensor is capable of sensing the different bed roughness.
M. D. Cowley and R. E. Rosensweig. The interfacial stability of a ferromagnetic fluid. Journal of Fluid Mechanics, 30(4):671-688, 1967. doi: 10.1017/S0022112067001697.
J. De Vicente, D. J. Klingenberg, and R. Hidalgo-Alvarez. Magnetorheological fluids: a review. Soft matter, 7(8):3701-3710, 2011.
C. Faraci, E. Foti, and R. E. Musumeci. Waves plus currents at a right angle: The rippled bed case. Journal of Geophysical Research: Oceans, 113(C7), 2008. doi: 10.1029/2007JC004468.
K. Y. Lim and O. S. Madsen. An experimental study on near-orthogonal wave-current interaction over smooth and uniform fixed roughness beds. Coastal Engineering, 116:258-274, 2016. ISSN 0378-3839. doi: https://doi.org/10.1016/j.coastaleng.2016.05.005.
C. Lo Re, R. E. Musumeci, and E. Foti. A shoreline boundary condition for a highly nonlinear boussinesq model for breaking waves. Coastal Engineering, 60:41 - 52, 2012. ISSN 0378-3839. doi: https://doi.org/10.1016/j.coastaleng.2011.08.003. URL http://www.sciencedirect.com/science/article/pii/S0378383911001530.
R. E. Musumeci, V. Marletta, B. Andó, S. Baglio, and E. Foti. Ferrofluid measurements of bottom velocities and shear stresses. Journal of Hydrodynamics, Ser. B, 27(1):150-158, 2015a. ISSN 1001-6058. doi: https://doi.org/10.1016/S1001-6058(15)60467-X.
R. E. Musumeci, V. Marletta, B. Andó, S. Baglio, and E. Foti. Measurement of wave near-bed velocity and bottom shear stress by ferrofluids. IEEE Transactions on Instrumentation and Measurement, 64(5): 1224-1231, May 2015b.
R. E. Musumeci, V. Marletta, A. Sanchez-Arcilla, and E. Foti. A ferrofluid-based sensor to measure bottom shear stresses under currents and waves. Journal of Hydraulic Research, 56(5):630-647, 2018. doi: 10.1080/00221686.2017.1397779.
S. Odenbach. Ferrofluids: magnetically controllable liquids. PAMM, 1(1):28-32, 2002. doi: 10.1002/ 1617-7061(200203)1:1<28::AID-PAMM28>3.0.CO;2-8.
L. M. Stancanelli, R. E. Musumeci, and E. Foti. Dynamics of gravity currents in the presence of surface waves. Journal of Geophysical Research: Oceans, 123(3):2254-2273, 2018. doi: 10.1002/ 2017JC013273.
A. Viviano, R. E. Musumeci, and E. Foti. A nonlinear rotational, quasi-2dh, numerical model for spilling wave propagation. Applied Mathematical Modelling, 39(3):1099 - 1118, 2015. ISSN 0307-904X. doi: https://doi.org/10.1016/j.apm.2014.07.030.
J. M. Wallace and P. V. Vukoslavcevic. Measurement of the velocity gradient tensor in turbulent flows. Annual Review of Fluid Mechanics, 42:157-181, 2010.