Laboratory Apparatus and Experiments

NWRA offers flexible and adaptive workspace for a wide variety of atmospheric and oceanographic physics experiments in its 2,250 sq ft fluid dynamics laboratory. The scientists and engineers at NWRA have extensive backgrounds in laboratory fluid mechanics measurements, flow visualization and computer modeling. The adjacent electronics laboratory supports the fluid laboratory efforts. Contact Don Delisi or Lee Piper about measuring or visualizing your experiment.

Calibrating Acoustic Velocimeters in a Non-Newtonian Fluid
at NWRA’s Fluid Laboratory.

Below is a list of some of the projects NWRA has researched in the fluid laboratory. Click on the images or links for more information about each of the apparatus.

Examples of research projects in the towing tank:

Generation and evolution of wing tip vortices in stratified and non-stratified fluids, with or without shear
Ring vortex evolution and merging
Generation of internal waves by towed objects or intrusions
Studies of double diffusive intrusions and salt fingering at NWRA’s Fluid Laboratory

Examples of research projects in the tilting tank:

Evolution of wing tip vortices in stratified, sheared flows
Generation and evolution of Kevin-Helmholtz and internal waves
Evolution and decay of turbulence in stratified, sheared flow

Click here for a video of Kelvin-Helmholtz waves in the tilting tank (3.8 MB AVI).

Examples of research projects in the annular tank:

Flow over topography
Topographical generation of internal waves
Interaction of internal waves with sheared fluids

Click here for a video of a solitary wave generated and phased to a towed surface keel in a step stratification in the annular tank (4.2 MB AVI).

Some of the instruments and equipment NWRA uses for research projects include:

Digital Particle Velocimetry Imaging (DPIV) system with 1000 by 480 pixel resolution
Digital and analog video cameras and frame grabbers
5-watt Argon-Ion laser and various flow visualization apparatus
Hot film anemometry system
50mm and 100mm water jets with variable flow velocity to 10m/s
Two tow carriage drives with speeds to 2.5 m/s
Mixing and stratification tanks and pumping systems
Recirculation pump with variable rate to 400 gpm

Fluid Laboratory Apparatus

A towing tank with glass walls and 2 drive systems is the versatile platform for many ocean and atmosphere physics experiments as well as instrumentation calibrations. The tank is 39 inches deep, 36 inches wide and 32 feet long, and can be stratified with salt water or some other medium. The dual tow system can drive carriages above the surface or can drive models and instruments below the surface. The tank can be used for NIST traceable velocity calibrations of flow instruments at tow speeds from 5 to 250 cm/sec. Glass walls allow visualization along entire length of the tank. A 400 gpm pumping system drives an underwater jet apparatus or can drive recirculation systems such as flows in flumes or pipes.

Flume with non-Newtonian fluid installed within the tow tank for specialized calibrations of velocity instruments.

Wing tip vortices descending in the tow tank. Nozzles on the side of the tank generate prescribed shear profiles.

Turbulence in wing tip vortices measured with hot film anemometry.

Contours of wing tip vorticity from digital particle imaging velocimetry.

The tilting "Thorpe" tank pivots on a centered fulcrum. This tank is 18 inches wide, 12 inches deep and 32 feet long. The tank can be stratified with salt water or some other medium. Acrylic walls allow flow visualization along the entire length of the tank.

Kelvin-Helmholtz waves in the tilting tank. This was a step stratification of salt water with a 2 cm interface and a grid at the left side of picture generating turbulence. Click here for animation

(3.8 MB AVI).

The annular tank has an articulating floor. This tank has a 1-foot circular channel on a 2.75 foot radius. Thirty-two pistons drive a deformable bottom to move topographical shapes around the annulus. Couette flows are generated with the rotating lid. A rotating camera mount tracks flow events. Experiments include generation of internal waves and their interaction with sheared flows.

Annular tank setup for an internal wave-critical layer interaction experiment. Internal waves interact with the stratified fluid sheared by a rotating lid. A rotating camera mount follows flow phenomena.

A solitary wave generated and phased to a towed surface keel in a step stratification in the annular tank. Distortions in the diagonal lines are due to the density gradient changes. Click here for animation

(4.2 MB AVI).