The Effect of Inlet Width on the Performance of Sediment Retention Ponds in Thermally Induced Flows

2021 ◽  
pp. 127377
Author(s):  
Ehsan Hendi ◽  
Asaad Y. Shamseldin ◽  
Bruce W. Melville
Keyword(s):  
Sediment Retention ◽  
Thermally Induced ◽  
Retention Ponds ◽  
Sediment Retention Ponds

scholarly journals Experimental investigation of the effect of temperature differentials on hydraulic performance and flow pattern of a sediment retention pond

2018 ◽  
Vol 77 (12) ◽  
pp. 2896-2906 ◽  
Author(s):  
Ehsan Hendi ◽  
Asaad Y. Shamseldin ◽  
Bruce W. Melville ◽  
Stuart E. Norris
Keyword(s):  
Residence Time ◽  
Hydraulic Performance ◽  
Effect Of Temperature ◽  
Sediment Retention ◽  
Small Temperature ◽  
Thermally Induced ◽  
Retention Pond ◽  
Retention Ponds ◽  
Sediment Retention Ponds ◽  
Counter Current

Abstract Existing studies on sediment retention ponds (SRPs) have examined the effects of pond layout, inlet and outlet geometry and the installation of baffles on the performance of the SRPs. However, the effects of a temperature difference between the ambient water in the pond and the inflow are often neglected, and the buoyancy forces arising from these differences in temperature can potentially change the flow in the pond and hence its hydraulic performance. This study has experimentally evaluated the effect of these temperature differences on the flow field and residence time in a retention pond for a range of temperature differences. As expected a cold inflow sinks to the bottom of the pond while a hot inflow remains at the surface, but in both cases the inflow flows more rapidly towards the outlet than is the case for isothermal inflow. A counter-current was observed at the bottom or the surface of the pond for colder or hotter influents, respectively. These thermally induced flows significantly reduced the residence time of the pond, reducing the hydraulic performance of the pond and causing severe short-circuiting. The results have also shown that the temperature differences in the pond decrease with time, yet small temperature differences persist with the pond remaining thermally stratified.

Evaluation of hydraulic performance indices for retention ponds

2015 ◽  
Vol 72 (1) ◽  
pp. 10-21 ◽  
Author(s):  
Arash Farjood ◽  
Bruce W. Melville ◽  
Asaad Y. Shamseldin ◽  
Keith N. Adams ◽  
Sher Khan
Keyword(s):  
Hydraulic Performance ◽  
Hydraulic Efficiency ◽  
Hydraulic Analysis ◽  
Performance Indices ◽  
Sediment Retention ◽  
Retention Pond ◽  
Retention Ponds ◽  
Sediment Retention Ponds ◽  
Moment Index ◽  
Selection Of

Abstract Comprehensive hydraulic analysis of sediment retention ponds is commonly achieved through interpretation of residence time distribution and derivation of indices associated with short-circuiting and mixing. However, the availability of various indices indicates the need for careful selection of the most appropriate indices. This study compares some of the commonly used hydraulic performance indices, together with a new short-circuiting index, τ5, for five different flow regimes in a model sediment retention pond. The results show that τ5 was the best measure for short-circuiting. Among the mixing indices, only the Morril index correctly represented the physical behaviour of the experiments. In addition, two hydraulic efficiency indices, λ and a moment index (MI) were assessed and showed a good correlation with the short-circuiting and mixing indices, but MI was more reproducible than λ. Based on these results, this study recommends using τ5, Morril index and MI for analysis of hydraulic performance in sediment retention ponds.

scholarly journals Effect of baffles on the hydraulic performance of sediment retention ponds

2016 ◽  
Vol 75 (9) ◽  
pp. 1991-1996
Author(s):  
Sher Khan ◽  
Bruce W. Melville ◽  
Mudasser Muneer Khan ◽  
Muhammad Shoaib ◽  
Asaad Shamseldin
Keyword(s):  
Physical Model ◽  
Residence Time ◽  
Hydraulic Performance ◽  
Large Area ◽  
Sediment Retention ◽  
Retention Pond ◽  
Retention Ponds ◽  
Sediment Retention Ponds

An investigation of the effect of baffles on retention pond performance using a physical model of an existing sediment retention pond is presented. Analysis of residence time (RTD curves) was used to compare the hydraulic performance of different arrangements of baffles in the pond. Five different arrangements for the design of baffles were studied. The results show that placing a single baffle to deflect the influent to a sediment retention pond does not improve pond performance; rather, it stimulates short-circuiting. This is contradictory to the literature and is considered to be a consequence of the model pond incorporating sloping walls, which is a novel aspect of this study. Most of the previous studies have neglected the effects of battered walls. Conversely, the inclusion of more than two baffles was found to increase the hydraulic performance. The results reported here are limited to small and narrow ponds where a large portion of the pond is batter (i.e. made up of sloping walls). For large area ponds, batter effects may be negligible and are likely to be different from those reported here.

Morphologies of Nonadherent Al2O3 and Matching Substrate Surfaces

1972 ◽  
Vol 30 ◽  
pp. 524-525
Author(s):  
C. S. Giggins ◽  
J. K. Tien ◽  
B. H. Kear ◽  
F. S. Pettit
Keyword(s):  
Electron Microscopy ◽  
Oxide Scale ◽  
Oxidation Resistance ◽  
Substrate Surface ◽  
Morphological Features ◽  
Thermally Induced ◽  
Oxide Spallation ◽  
Oxidation Resistant ◽  
Induced Stresses ◽  
Substrate Surfaces

The performance of most oxidation resistant alloys and coatings is markedly improved if the oxide scale strongly adheres to the substrate surface. Consequently, in order to develop alloys and coatings with improved oxidation resistance, it has become necessary to determine the conditions that lead to spallation of oxides from the surfaces of alloys. In what follows, the morphological features of nonadherent Al2O3, and the substrate surfaces from which the Al2O3 has spalled, are presented and related to oxide spallation.The Al2O3, scales were developed by oxidizing Fe-25Cr-4Al (w/o) and Ni-rich Ni3 (Al,Ta) alloys in air at 1200°C. These scales spalled from their substrates upon cooling as a result of thermally induced stresses. The scales and the alloy substrate surfaces were then examined by scanning and replication electron microscopy.The Al2O3, scales from the Fe-Cr-Al contained filamentary protrusions at the oxide-gas interface, Fig. 1(a). In addition, nodules of oxide have been developed such that cavities were formed between the oxide and the substrate, Fig. 1(a).

Applications of ultramicrotomy for materials characterization

1993 ◽  
Vol 51 ◽  
pp. 232-233
Author(s):  
R.T. Blackham ◽  
J.J. Haugh ◽  
C.W. Hughes ◽  
M.G. Burke
Keyword(s):  
Materials Science ◽  
Microstructural Analysis ◽  
Analytical Electron Microscopy ◽  
Austenitic Stainless Steels ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Thermally Induced ◽  
Radiation Induced ◽  
Characterization Of Materials

Essential to the characterization of materials using analytical electron microscopy (AEM) techniques is the specimen itself. Without suitable samples, detailed microstructural analysis is not possible. Ultramicrotomy, or diamond knife sectioning, is a well-known mechanical specimen preparation technique which has been gaining attention in the materials science area. Malis and co-workers and Glanvill have demonstrated the usefulness and applicability of this technique to the study of a wide variety of materials including Al alloys, composites, and semiconductors. Ultramicrotomed specimens have uniform thickness with relatively large electron-transparent areas which are suitable for AEM anaysis.Interface Analysis in Type 316 Austenitic Stainless Steel: STEM-EDS microanalysis of grain boundaries in austenitic stainless steels provides important information concerning the development of Cr-depleted zones which accompany M23C6 precipitation, and documentation of radiation induced segregation (RIS). Conventional methods of TEM sample preparation are suitable for the evaluation of thermally induced segregation, but neutron irradiated samples present a variety of problems in both the preparation and in the AEM analysis, in addition to the handling hazard.

Spin-crossover in an iron(iii) complex showing a broad thermal hysteresis

2021 ◽  
Author(s):  
Cyril Rajnák ◽  
Romana Mičová ◽  
Ján Moncoľ ◽  
Ľubor Dlháň ◽  
Christoph Krüger ◽  
...  
Keyword(s):  
Schiff Base ◽  
Schiff Base Ligand ◽  
Spin Crossover ◽  
Thermal Hysteresis ◽  
Mononuclear Complex ◽  
Hysteresis Width ◽  
Thermally Induced

A pentadentate Schiff-base ligand 3,5Cl-L2− and NCSe− form a iron(iii) mononuclear complex [Fe(3,5Cl-L)(NCSe)], which shows a thermally induced spin crossover with a broad hysteresis width of 24 K between 123 K (warming) and 99 K (cooling).

Thermally induced budding of phospholipid vesicles — a discontinuous process

1993 ◽  
Vol 3 (5) ◽  
pp. 631-645 ◽  
Author(s):  
J. Käs ◽  
E. Sackmann ◽  
R. Podgornik ◽  
S. Svetina ◽  
B. Žekš
Keyword(s):  
Phospholipid Vesicles ◽  
Thermally Induced ◽  
Discontinuous Process
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