University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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Turbulent flow

Classification: Manifold process -> Turbulent flow

Citations 9

"Virtual Plume"
Electroanalysis 2000 Volume 12, Issue 12 Pages 974-979
Timo Kikas, Hiroshi Ishida, Philip J. W. Roberts, Donald R. Webster, Jiri Janata

Abstract: A bench-top model of a chemical plume in a turbulent flow, a Virtual Plume, was built to simulate the behavior of a turbulent chemical plume. It is based on an eight-channel FIA/SIA system and an array of eight amperometric sensors. A plug of sample solution was delivered to me sensors after passing through delay and dispersion elements. Adjusting these two elements enabled us to simulate the rime-concentration profile at any arbitrary point in the plume. It has been shown that an eight-channel system can simulate an arbitrary sensor array positioned in a turbulent plume. Preliminary correlation of the shape of the peaks obtained in the VP with those recorded using planar laser-induced fluorescence in a turbulent flow shows the value of this approach.

"Turbulent Hydrodynamic Voltammetry. 3. Analytical Investigations With A Turbulent Voltammetric Cell And Applications To Amino Acid Analysis"
Anal. Chim. Acta 1977 Volume 94, Issue 2 Pages 351-356
M. Varadi and E. Pungor

Abstract: The analytical applicability of a turbulent voltammetric cell in a flowing stream has been studied. A silicone rubber-based graphite electrode is used. Under optimal conditions, the distortion of the signal in the cell as well as the fluctuations of the signal cause a relative standard deviation of 1% in the results. An examination of the amino acids which occur in protein hydrolyzates is reported. Proline, histidine and arginine can be determined with standard deviations of about 4%; the standard deviations range from 10% to 16% for the other amino acids, except threonine, serine and tyrosine which cannot be determined.
Amino Acids Arginine l-Proline Histidine Electrode Voltammetry

"Immunological Online Detection Of Specific Proteins During Fermentation Processes"
Anal. Chim. Acta 1991 Volume 249, Issue 1 Pages 113-122
Ruth Freitag, Christel Fenge, Thomas Scheper, Karl Schügerl, Andreas Spreinat, Garo Antranikian and Elisabeth Fraune

Abstract: A merging zones stopped-flow flow injection system is described (with diagram) for online immunoturbidimetric determination of proteins in fermentation processes. Sample and reagent solution are injected into separate buffer streams, the streams are merged and the flow is stopped to allow incubation at 37°C. After incubation, turbidity is measured at 340 nm vs. a sample blank. For determination of monoclonal IgG, the reagent solution (0.1 mL min-1) was anti-mouse IgG (1.8 mg mL-1), the buffer solution (1 mL minmin1) was 0.01 M sodium phosphate buffer solution (pH 7.2) containing PEG 6000 (30 g l-1) and NaCl (4.5 g l-1) and the incubation time was 90 s. For assay of α-dextrin endo-1,6-α-glucosidase (I), the reagent was rabbit anti-I antibody solution, the buffer solution was the same as that for IgG, but with 40 g L-1 of PEG 6000, and the incubation time was 120 s. From 10 to 1000 iu L-1 of I and 1 to 1000 mg L-1 of IgG could be determined.
Proteins Fermentation broth Turbidimetry

"Turbulent Flow Chromatography: A New Approach To Faster Analysis"
Anal. Chem. 1966 Volume 38, Issue 2 Pages 274-281
Victor Pretorius and T. W. Smuts

Abstract: Expressions have been derived for plate height and minimum analysis time in open tubular columns in which laminar and turbulent flow of the mobile phase may be employed. Using these equations the role of various column parameters in fast analysis has been studied in laminar and turbulent flow regions of gas and liquid chromatography. In the gas chromatography turbulent flow can lead to analysis times about one tenth of those obtained under comparable circumstances by using laminar flow. In liquid chromatography turbulence can shorten analysis times by as much as a factor of 10^4. In general turbulent flow chromatography entails the use of slightly longer column lengths and much larger pressure drops than would be needed under similar conditions in laminar chromatography.
GC LC

"Long-optical-path Thin-layer Spectroelectrochemistry In A Liquid Chromatographic Ultra-violet - Visible Absorbance Detector Cell"
Anal. Chem. 1991 Volume 63, Issue 22 Pages 2668-2672
Thomas R. Nagy and James L. Anderson

Abstract: Spectroelectrochemical cells based on a long-optical-path thin-layer electrode (LOPTLE) with the optical beam parallel to the surface of the electrode exhibit problems in respect of material compatibility, optical alignment and optical signal-to-noise ratio. A tubular flow-through LOPTLE cell, incorporated in a conventional HPLC UV detector cell, is reported to overcome these limitations by taking advantage of the optimized optical alignment and signal-to-noise ratio. Flow injection analysis indicated that detection limits for various analytes are improved tenfold and that the coefficient of variation is improved from 1.1% for the non-tubular flow-through cell to 0.2%. Multi-potential-step chronoabsorptiometry was used to perform a stopped-flow spectropotentiostatic experiment for Fe(CN)63-; again the detection limits was improved by a factor of 10 as compared with other thin-layer cells.
HPLC Electrochemical analysis Spectrophotometry Spectroelectrochemistry

"Pulsed Flow Chemistry. A New Approach To The Generation Of Concentration Profiles In Flow Analysis"
Anal. Commun. 1998 Volume 35, Issue 3 Pages 97-101
Xue D. Wang, Terence J. Cardwell, Robert W. Cattrall and Graeme E. Jenkins

Abstract: Pulsed flow chemical (PFC) is described as a new approach to automated online anal. chemical In contrast to existing flow-based anal. chemical methods, PFC is characterized by pulsed flow, turbulent mixing and low axial dispersion. The PFC system is fully computerized and all operations are under software control. Consequently, most flow analysis methods (e.g., flow injection, continuous-flow, flow titration, etc.) can be selected with a simple click of the mouse. The system is easily miniaturized and portable which makes it particularly suited to field instrumentation. The system has been tested using several flow-based techniques including online titration for the determination of calcium in waters with potentiometric detection and a calcium ion sensor.
Calcium Environmental Potentiometry

"Longitudinal Mixing Of Fluids Flowing In Circular Pipes"
Ind. Eng. Chem. 1958 Volume 50, Issue 3 Pages 343-346
Octave Levenspiel

Abstract: Charts which were based on the assumption that longitudinal fluid mixing is analogous to the process of diffusion were constructed by using data from literature. These data, which were obtained under widely varying conditions, fell in a narrow band in the turbulent region. However, the charts have only limited application in the streamline region. The diffusion model is based on the use of a straight pipe, which most of the data used did not satisfy. Pipe roughness and curvature have been shown to increase mixing. Further experimentation was recommended for the streamline region, to narrow the range of uncertainty in the curves used in the turbulent region, and to determination the role of the Schmidt number at low Reynolds numbers.

"Indicator Dilution Measurement Of Mean Transit Time And Flow In A Straight Tube"
J. Phys. E 1974 Volume 7, Issue 1 Pages 51-55
D A Lane and J A Sirs

Abstract: A theoretical analysis has been undertaken of the application of an indicator dilution technique, using bolus injection, to the measurement of flow rate, mean transit time and vessel volume in a straight tube, for both mixed and laminar flow. Under laminar flow conditions, formulae previously utilized may be substantially wrong. Alternative methods and formulae are proposed and experimental confirmation made of their validity over a wide range of flow conditions.
Spectrophotometry

"Dispersion Of Matter In Turbulent Flow-through A Pipe"
Proc. Royal Soc. A 1954 Volume 223, Issue 1155 Pages 446-468
Geoffrey Taylor

Abstract: The dispersion of soluble matter introduced into a slow stream of solvent in a capillary tube can be described by means of a virtual coefficient of diffusion (Taylor 1953a) which represents the combined action of variation of velocity over the cross-section of the tube and molecluar diffusion in a radial direction. The analogous problem of dispersion in turbulent flow can be solved in the same way. In that case the virtual coefficient of diffusion K is found to be 10⋅1av* or K = 7.14aU√γ. Here a is the radius of the pipe, U is the mean flow velocity, g is the resistance coefficient and v* 'friction velocity'. Experiments are described in which brine was injected into a straight 3/8 in. pipe and the conductivity recorded at a point downstream. The theoretical prediction was verified with both smooth and very rough pipes. A small amount of curvature was found to increase the dispersion greatly. When a fluid is forced into a pipe already full of another fluid with which it can mix, the interface spreads through a length S as it passes down the pipe. When the interface has moved through a distance X, theory leads to the formula S^2 = 437aX(v*/U). Good agreement is found when this prediction is compared with experiments made in long pipe lines in America.
Environmental