TY - JOUR

T1 - Added mass

T2 - A complex facet of tidal conversion at finite depth

AU - Brouzet, C.

AU - Ermanyuk, E. V.

AU - Moulin, M.

AU - Pillet, G.

AU - Dauxois, T.

PY - 2017/11/25

Y1 - 2017/11/25

N2 - This paper revisits the problem of tidal conversion at a ridge in a uniformly stratified fluid of limited depth using measurements of complex-valued added mass. When the height of a sub-marine ridge is non-negligible with respect to the depth of the water, the tidal conversion can be enhanced in the supercritical regime or reduced in the subcritical regime with respect to the large depth situation. Tidal conversion can even be null for some specific cases. Here, we study experimentally the influence of finite depth on the added mass coefficients for three different ridge shapes. We first show that, at low forcing frequency, the tidal conversion is weakly enhanced by shallow depth for a semi-circular ridge. In addition, added mass coefficients measured for a vertical ridge show strong similarities with the ones obtained for the semi-circular ridge. Nevertheless, the enhancement of the tidal conversion at low forcing frequency for the vertical ridge has not been observed, in contrast with its supercritical shape. Finally, we provide the experimental evidence of a lack of tidal conversion due to the specific shape of a ridge for certain depth and frequency tuning.

AB - This paper revisits the problem of tidal conversion at a ridge in a uniformly stratified fluid of limited depth using measurements of complex-valued added mass. When the height of a sub-marine ridge is non-negligible with respect to the depth of the water, the tidal conversion can be enhanced in the supercritical regime or reduced in the subcritical regime with respect to the large depth situation. Tidal conversion can even be null for some specific cases. Here, we study experimentally the influence of finite depth on the added mass coefficients for three different ridge shapes. We first show that, at low forcing frequency, the tidal conversion is weakly enhanced by shallow depth for a semi-circular ridge. In addition, added mass coefficients measured for a vertical ridge show strong similarities with the ones obtained for the semi-circular ridge. Nevertheless, the enhancement of the tidal conversion at low forcing frequency for the vertical ridge has not been observed, in contrast with its supercritical shape. Finally, we provide the experimental evidence of a lack of tidal conversion due to the specific shape of a ridge for certain depth and frequency tuning.

KW - internal waves

KW - stratified flows

KW - topographic effects

UR - http://www.scopus.com/inward/record.url?scp=85031941005&partnerID=8YFLogxK

U2 - 10.1017/jfm.2017.616

DO - 10.1017/jfm.2017.616

M3 - Article

AN - SCOPUS:85031941005

VL - 831

SP - 101

EP - 127

JO - Journal of Fluid Mechanics

JF - Journal of Fluid Mechanics

SN - 0022-1120

ER -