Environmental Fluid Dynamics Education Laboratory
Honolulu, HI 96822
Geno Pawlak email: gpawlak X ore.hawaii.edu
The dynamics of moving fluids forms the physical basis of the natural environment through the ocean and atmosphere, in turn affecting biological, chemical and geological systems. Fluid motion is also fundamental to engineering problems ranging from aerodynamics to biomedical research. The concepts of fluid dynamics are not learned from textbooks and equations alone, however. These ideas require hands-on experience and observation that complements classroom learning. The goal of the Environmental Fluid Dynamics Education Laboratory (EFDEL) is to serve as a center for teaching of fluids phenomena for SOEST and the general UHM community.
The EFDEL offers support for laboratory demonstration of environmental and geophysical fluid dynamics phenomena. We have carried out lab experiments as part of ORE 601 (Ocean and Resources Engineering Laboratory), ORE 664 (Nearshore Processes and Sediment Transport) and have conducted demonstrations for ORE 603 (Oceanography for Ocean Engineers), ORE 641 (Environmental Fluid Dynamics) and OCN 620 (Physical Oceanography) as well as for visiting high school students from the Sea Grant Ocean Learning Academy and for the SOEST Open House. A sample of the variety of fluids experiments are shown below.
Links to other fluids labs:
Geophysical Fluid Dynamics Laboratory, University of Washington (Peter Rhines, Eric Lindahl)
Environmental Fluid Mechanics Laboratory, Stanford University
Intrusion generated by boundary mixing in a two layer fluid
Equipotential surface in a rotating flow
Ripples under a standing wave
SOEST Open House
Boundary Mixing / Intrusions
Waves and tides generate significant motion along
the bottom that can generate strong mixing and lead to lateral variations in the
density field which, in turn, drive horizontal flows.
In the photo sequence below, turbulence is generated by an oscillating grid
along a slope. The tank filled with two layers with differing
salinities (and thus different density). A third layer of mixed fluid develops and
propagates between the two initial layers. This is visualized by injecting
fluorescing dye through the moving grid between the two layers and using 'black'
Salt fingers are a double diffusive phenomena that are created as a result of the differing diffusive rates for salt and temperature. They can be produced by carefully pouring warmer and saltier water (blue) above cooler and less salty water. Initially, a stable density gradient exists due to the variation in temperature. Since the temperature diffusion is faster than the diffusion of salt, dense cool and salty water is created at the interface between the two fluids which sinks in the form of narrow fingerlike plumes.
Because the earth is rotating, the Coriolis and centrifugal forces play important roles in many environmental fluid dynamics problems. A rotating table can be used to demonstrate phenomena like Ekman pumping, Taylor columns and conservation of vorticity.
Ekman layer visualization in spin-down
RIpple Dynamics under Standing Waves
This experiment examines the response of various sediment particles to oscillating flow under a standing wave.
Fine grained sediments
Medium grained sediments
Coarse grained sediments
Wave Driven Porewater Exchange
Wave induced motion does not end at the bed surface. Waves also create pressure gradients within the sediment bed that can generate significant flows. These porewater flows can drive exchanges between the sediment bed and water column that have important effects on benthic ecosystems. Dye traces (below) outline the paths for fluid within the bed in response to ripples at the bed surface.
Particle Settling in Laminar and Turbulent Flow
Settling velocity is a key dynamic quantity of interest in sediment transport. The goal of this experiment is to explore the relationship between settling velocities and turbulence for a variety of sediment particles
Credits: Special thanks to Fabian Schloesser for his assistance in carrying out many of the experiments and assembling this page. Also thanks to Jerome Aucan for his work on the boundary mixing experiment and to Andy Hebert for his work on the porewater experiments.