Shear probes

Turbulence Shear Spectra

A discussion of the theoretical and empirical expectations of the spectrum of shear in isotropic turbulence is presented here.

Flow chart for dissipation estimates using shear probes

The processing of shear-probe data can be divided into the following five major steps and these steps apply to data collected with any platform or vehicle. There are many sub-steps to these major steps. The major steps are;

1. Conversion to physical units.

   • Determine the speed of profiling of the shear-probe through the water.
   • Determine the temperature of the water.
   • Convert the shear-probe data samples into physical units
   • Convert all other signals per the recommendations of the manufacturer of the sensor or instruments that produce these signals.

2. Profile selection.

   Before you can process your shear-probe data to derive the rate of dissipation you must select the segment of data that you wish to process. You must make sure that the selection is meaningful and sensible. For example, the shear probe most must be profiling through the water with a speed, direction, and orientation that is fairly stationary. The selection of data can be partially automated by requiring that the kinematics of your instrument achieve certain minimum criteria. The steps to profile selection are as follows:

   • Choose the minimum speed of profiling.
   • Choose the direction of the vertical velocity of the profiler.
   • Choose the minimum depth.
   • Choose the maximum pitch and roll of the profiler.
   • Choose the minimum duration over which the minimum speed through maximum pitch and roll must be satisfied.

3. Choosing the processing parameters.
4. Dissipation rate estimation.
5. Applying quality-control metrics.