SY055-10
An Experimental Facility to Generate Homogeneous Isotropic Turbulence and Investigate Ice Melting Rates

Wednesday, 16 December 2020: 17:58
Virtual
Aubrey McCutchan, University of Texas at Austin, Austin, TX, United States and Blair A Johnson, University of Texas at Austin, Department of Civil, Architectural, and Environmental Engineering, Cockrell School of Engineering, Austin, TX, United States
Abstract:
Currently absent from the literature is a thorough quantification of the effect turbulence has on ice melting rates pertaining to ice sheet-ocean interactions. To understand the underlying physics of turbulence on melting rates, we designed an experimental apparatus that generates homogeneous isotropic turbulence (HIT). Based upon the work of Variano and Cowen (2008) and Johnson & Cowen (2018), a random jet array is used to create HIT absent mean flow within the center of a tank. The cube tank was constructed with a total of twenty jets, one located at each tank corner and edge midpoint. The jets were secured on a PVC frame that sits within the tank. Nozzles located on the outlets of the jets directed water into the center of the tank where a core of HIT was generated.

Particle image velocimetry (PIV) was used to measure turbulence levels within the experimental tank. Statistical analysis of PIV data provided turbulence metrics including mean and turbulent velocities, turbulent kinetic energy, spectra, integral scales, dissipation, Kolmogorov length and time scales, and the Taylor scale Reynolds number. The new facility required testing a variety of parameter combinations of the jet forcing algorithm and pump outlet conditions to create an ideal turbulent environment. Initial measurements were completed to determine the length of an individual jet varying jet voltage and on time to inform HIT generation using the random jet array.

To understand the effect of varying levels of HIT on ice melting rates, a sphere of ice was secured stationary within the tank using a metal rod attached to a tank lid. HIT was generated around the ice sphere and the melting rate was determined using image analysis of tank-lapse photography of the sphere. Furthermore, to test the effect of ambient water temperature in combination with HIT on melting rates, the water temperature in the facility was varied from 0 to 10 degrees Celsius.

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