A baroclinic, convective mixed-layer was modeled, using
water, in a laboratory convection tank identical to that
used in the free convection study of Deardorff and Willis
(1985). Baroclinicity and mean-flow shearing were achieved
by tilting the tank by an angle of 1O⁰. The resulting
mechanical-production rate of turbulence kinetic energy was
comparable in magnitude to the buoyancy-production rate at
mid-levels within the mixed-layer.
Velocities were obtained by taking time-lapse
photographs of neutrally-buoyant oil droplets suspended in
the mixed-layer fluid. Variances and other statistical
descriptors of the turbulence obtained from these
velocities are presented in comparison to the free
convection results of Deardorff and Willis (1985). The
deviation of the present results from those of Deardorff
and Willis (1985) are assumed to be related to the effects
of mean-flow shearing and are explained wherever possible
with the aid of an appropriate kinetic energy budget
(kinetic energy, here, refers to the kinetic energy of the
turbulence and is not to be confused with the kinetic
energy of the mean-flow).
The results indicate that a maximum in downstream
horizontal kinetic energy at mid-levels within the mixed layer
was generated by shear-production and, also, by
conversion from vertical kinetic energy. In the lower
mixed-layer, vertical kinetic energy was amplified by a
mechanical-production term associated with the divergence
of the mean vertical velocity. Total turbulence kinetic
energy, normalized by the square of the convective velocity
scale, was much larger at mid-levels than in Deardorff and
Willis (1985) due to mechanical-production which is not
accounted for by simple mixed-layer scaling. Horizontal
turbulence structure was predominately controlled by
convection while vertical turbulence structure was
significantly altered by mean-flow shearing. / Graduation date: 1989
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/28617 |
| Date | 09 February 1989 |
| Creators | Nance, Jon D. |
| Contributors | Deardorff, James W. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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