Turbulent chemical plume

Dasi, L. P. Statistical Characteristics of Turbulent Chemical Plumes. Master s Thesis, Georgia Institute of Technology, Atlanta, Georgia, July 2000. 

Several laboratory studies have contributed to our understanding of turbulent chemical plumes and the effects of various flow configurations. Fackrell and Robins [25] released an isokinetic neutrally buoyant plume in a wind tunnel at elevated and bed-level locations. Bara et al. [26], Yee et al. [27], Crimaldi and Koseff [28], and Crimaldi et al. [29] studied plumes released in water channels from bed-level and elevated positions. Airborne plumes in atmospheric boundary layers also have been studied in the field by Murlis and Jones [30], Jones [31], Murlis [32], Hanna and Insley [33], Mylne [34, 35], and Yee et al. [36, 37], In addition, aqueous plumes in coastal environments have been studied by Stacey et al. [38] and Fong and Stacey [39], The combined information of these and other studies reveals that the plume structure is influenced by several factors including the bulk velocity, fluid environment, release conditions, bed conditions, flow meander, and surface waves. 

WEISSBURG, M.J., DUSENBERY, D.B., ISHIDA, H. JANATA, J. KELLER, T., ROBERTS, P.J.W. WEBSTER, D.R., A multidisciplinary study of spatial and temporal scales containing information in turbulent chemical plume tracking. Environ. Fluid Mech, 2002, 2, 65-94. 

Example 3.4 A turbulent fire plume is experimentally found to bum with 10 times the required stoichiometric air up to the tip of the flame. It is also measured that 20 % of the chemical energy is radiated to the surroundings from the flame. The fuel is methane, which is supplied at 25 °C and burns in air which is also at 25 °C. Calculate the average temperature of the gases leaving the flame tip. Assume constant and equal specific heats and steady state. 

The results demonstrate (i) that in turbulent odor plumes, purely chemical spatial gradients can be calculated when measuring with sensors scaled to lobster olfactory organs, (ii) that rapid odor access to the lobster s olfactory organs (under low ambient flow conditions) is accom-... 

Webster, D. R. and Weissburg, M. J. (2001). Chemosensory guidance cues in a turbulent chemical odor plume. Limnology and Oceanography 46,1034-1047. 

Figure 5.1 shows a photograph of a chemical plume in a turbulent water flow. The dye in this example has been released from a small orifice upstream of... 

Based on the discussed example parameters that influence the turbulent mixing process, it is clear that plume structure can be described in general terms, but the specific characteristics are likely to be case dependent. Nevertheless, certain characteristics, such as those employed by the odor-gated rheotaxis with bilateral comparison strategy, may be similar enough to allow animals and engineered systems to track chemical plumes for a wide range of flow conditions. 

Webster, D. R., S. Rahman, and L. P. Dasi. On the usefulness of bilateral comparison to tracking turbulent chemical odor plumes. Limnol. Oceanogr. 46, 1048-1053... 

Moore, P. A., N. Scholz, and J. Atema. Chemical orientation of lobsters, Homarus americanus, in turbulent odor plumes. 7. Chem. Ecol. 17, 1293-1307 (1991). 

Georgia Institute of Technology School of Civil/Environmental Engineering 790 Atlantic Drive Atlanta, GA, 30332 Ph 404.894.6704 (Dr. Donald Webster) www.ce.gatech. edu Environmental fluid mechanics and turbulence of chemical plumes. 

Fig. 10.14 Chemical plume of red dye spreading in turbulent stream. Highlighted sensors from the array are positioned downstream from the nozzle at distances LI and L2. They are selected for correlation analysis...

Figure 10. Projects controllable wind tunnel installation for chemical source locaUsation experiments and chemosensing robot with sensor array. By nsing arrays of speed controllable axial fans we are able to reproduce the S -shaped chemical plumes that result from changing wind direction in the natural environment. Dedicated flow control enables ns to test from highly laminar throngh to turbulent and unsteady flow conditions.

Many organisms are exposed to some of the thermal, chemical, and physical stresses of entrainment by being mixed at the discharge with the heated water this is plume entrainment. The exact number exposed depends on the percentage of temperature decline at the discharge that is attributed to turbulent mixing rather than to radiative or evaporative cooling to the atmosphere. 

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