Chute Performance and Design for Rapid Flow Conditions

2003 ◽  
Vol 26 (2) ◽  
pp. 163-170 ◽  
Author(s):  
A.W. Roberts
Keyword(s):  
Flow Conditions ◽  
Rapid Flow

Experimental abatement data of underflow baffles for removal of floatables in the CSOs of the Greater Montréal (Canada) area

2005 ◽  
Vol 51 (2) ◽  
pp. 65-70 ◽  
Author(s):  
John F. Cigana ◽  
Martin Couture
Keyword(s):  
Pilot Scale ◽  
Horizontal Velocity ◽  
Design Criteria ◽  
Operational Cost ◽  
Flow Conditions ◽  
Combined Sewer Overflows ◽  
Follow Up Study ◽  
Combined Sewer ◽  
Rapid Flow

Underflow baffles have gained in popularity over the years as a viable mean to intercept floatables in Combined Sewer Overflows (CSOs). This choice was mainly justified by the extremely low capital cost (CAPEX) and operational cost (OPEX) of this solution, although the efficiency of underflow baffles has never been clearly proven. The only similar application to underflow baffles are scum boards in grit chambers and clarifier. However, the flow conditions at CSOs vary considerably from those in grit chambers and clarifier. For this reason, review of the behavior of floatables in a rapid flow is paramount. Only then can comprehensive design criteria for underflow baffles and overflow chambers be suggested. Pilot scale tests, performed in a 17 metres long basin at various flowrates, had already shown that a critical horizontal velocity for floatables (Vcr) may develop in the overflow chambers. In this follow up study, the fate of intercepted floatables was investigated. It appears from this latest data that permanent capture of floatables decreases rapidly with an increase in the horizontal velocity of the flow, no matter what the baffle depth. Baffle depth increases capture at lower velocities (0.17 m/s) but become irrelevant at higher velocities (0.61 m/s). This data suggests that capture efficiency of existing underflow baffles in overflow chambers can be, at best, very low whenever the horizontal velocity increases above 0.30 m/s or 1 ft/s.

Non-local continuum modelling of steady, dense granular heap flows

2017 ◽  
Vol 831 ◽  
pp. 212-227 ◽  
Author(s):  
Daren Liu ◽  
David L. Henann
Keyword(s):  
Flow Rate ◽  
Creeping Flow ◽  
Decay Length ◽  
Flow Conditions ◽  
Rate Dependent ◽  
Continuum Modelling ◽  
Rapid Flow ◽  
Dense Granular Flow ◽  
Non Local ◽  
Side Walls

Dense granular heap flows are common in nature, such as during avalanches and landslides, as well as in industrial flows. In granular heap flows, rapid flow is localized near the free surface with the thickness of the rapidly flowing layer dependent on the overall flow rate. In the region deep beneath the surface, exponentially decaying creeping flow dominates with characteristic decay length depending only on the geometry and not the overall flow rate. Existing continuum models for dense granular flow based upon local constitutive equations are not able to simultaneously predict both of these experimentally observed features – failing to even predict the existence of creeping flow beneath the surface. In this work, we apply a scale-dependent continuum approach – the non-local granular fluidity model – to steady, dense granular flows on a heap between two smooth, frictional side walls. We show that the model captures the salient features of both the flow-rate-dependent, rapidly flowing surface layer and the flow-rate-independent, slowly creeping bulk under steady flow conditions.

Effects of Metals and Metal Oxides on the Leaching of Nuclear Waste Glasses

1983 ◽  
Vol 26 ◽  
Author(s):  
Aaron Barkatt ◽  
William Sousanpour ◽  
Alisa Barkatt ◽  
Morad A. Boroomand
Keyword(s):  
Stainless Steel ◽  
Metal Oxides ◽  
Nuclear Waste ◽  
Waste Glass ◽  
Flow Conditions ◽  
Dissolved Silica ◽  
Waste Package ◽  
Beneficial Role ◽  
Rapid Flow

ABSTRACTThe effects of the presence of various metals and metal oxides on the leaching of nuclear waste glasses in water can be considerable even under rapid flow conditions. The systems studied here include SRL TDS-131 glass in the presence of lead and stainless steel, and PNL 76-68 glass in the presence of aluminum, alumina and their mixtures. Lead specifically suppresses dissolved silica, but does not inhibit dissolution of defense waste glass as a whole. Stainless steel specifically reduces the levels of dissolved Ca and Sr. Al and Al2 O3 exercise a general reducing effect on the rates of dissolution of commercial waste glass and the presence of alumina may have a beneficial role in enhancing waste package durability.

Calibration of cohesive DEM parameters under rapid flow conditions and low consolidation stresses

2020 ◽  
Vol 374 ◽  
pp. 22-32
Author(s):  
Mohsin Ajmal ◽  
Thomas Roessler ◽  
Christian Richter ◽  
André Katterfeld
Keyword(s):  
Flow Conditions ◽  
Rapid Flow

scholarly journals Optimized and validated flow-injection spectrophotometric analysis of topiramate, piracetam and levetiracetam in pharmaceutical formulations

2011 ◽  
Vol 61 (4) ◽  
pp. 377-389 ◽  
Author(s):  
Ghada Hadad ◽  
Randa Abdel-Salam ◽  
Samy Emara
Keyword(s):  
Flow Injection ◽  
Limit Of Detection ◽  
Pharmaceutical Preparations ◽  
Pharmaceutical Formulations ◽  
Spectrophotometric Analysis ◽  
Range Limit ◽  
Flow Conditions ◽  
Five Factors ◽  
Rapid Flow

Optimized and validated flow-injection spectrophotometric analysis of topiramate, piracetam and levetiracetam in pharmaceutical formulationsApplication of a sensitive and rapid flow injection analysis (FIA) method for determination of topiramate, piracetam, and levetiracetam in pharmaceutical formulations has been investigated. The method is based on the reaction withortho-phtalaldehyde and 2-mercaptoethanol in a basic buffer and measurement of absorbance at 295 nm under flow conditions. Variables affecting the determination such as sample injection volume, pH, ionic strength, reagent concentrations, flow rate of reagent and other FIA parameters were optimized to produce the most sensitive and reproducible results using a quarter-fraction factorial design, for five factors at two levels. Also, the method has been optimized and fully validated in terms of linearity and range, limit of detection and quantitation, precision, selectivity and accuracy. The method was successfully applied to the analysis of pharmaceutical preparations.

Thrombus formation on artificial surfaces: Correlative microscopy

1990 ◽  
Vol 48 (3) ◽  
pp. 840-841
Author(s):  
Quintin J. Lai ◽  
Stuart L. Cooper ◽  
Ralph M. Albrecht
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Low Voltage ◽  
Thrombus Formation ◽  
Blood Platelets ◽  
Polymer Surfaces ◽  
Flow Conditions ◽  
Transmission Electron ◽  
Adhesion Of Platelets ◽  
Microscopic Techniques

Thrombus formation and embolization are significant problems for blood-contacting biomedical devices. Two major components of thrombi are blood platelets and the plasma protein, fibrinogen. Previous studies have examined interactions of platelets with polymer surfaces, fibrinogen with platelets, and platelets in suspension with spreading platelets attached to surfaces. Correlative microscopic techniques permit light microscopic observations of labeled living platelets, under static or flow conditions, followed by the observation of identical platelets by electron microscopy. Videoenhanced, differential interference contrast (DIC) light microscopy permits high-resolution, real-time imaging of live platelets and their interactions with surfaces. Interference reflection microscopy (IRM) provides information on the focal adhesion of platelets on surfaces. High voltage, transmission electron microscopy (HVEM) allows observation of platelet cytoskeletal structure of whole mount preparations. Low-voltage, high resolution, scanning electron microscopy allows observation of fine surface detail of platelets. Colloidal gold-labeled fibrinogen, used to identify the Gp Ilb/IIIa membrane receptor for fibrinogen, can be detected in all the above microscopies.

Hydrodynamic flow conditions through permeable walls

1992 ◽  
Vol 2 (8) ◽  
pp. 1565-1569
Author(s):  
S. Vollmar ◽  
J. A. M. S. Duarte
Keyword(s):  
Hydrodynamic Flow ◽  
Flow Conditions ◽  
Permeable Walls

Platelet and Shear Rate Promote Tumor Cell Adhesion to Human Endothelial Extracellular Matrix - Absence of a Role for Platelet Cyclooxygenase

1989 ◽  
Vol 61 (03) ◽  
pp. 485-489 ◽  
Author(s):  
Eva Bastida ◽  
Lourdes Almirall ◽  
Antonio Ordinas
Keyword(s):  
Cell Adhesion ◽  
Shear Rate ◽  
Tumor Cell ◽  
Umbilical Vein ◽  
Blood Platelets ◽  
Flow Conditions ◽  
Tumor Cell Adhesion ◽  
Rate Dependent ◽  
Static Conditions

SummaryBlood platelets are thought to be involved in certain aspects of malignant dissemination. To study the role of platelets in tumor cell adherence to vascular endothelium we performed studies under static and flow conditions, measuring tumor cell adhesion in the absence or presence of platelets. We used highly metastatic human adenocarcinoma cells of the lung, cultured human umbilical vein endothelial cells (ECs) and extracellular matrices (ECM) prepared from confluent EC monolayers. Our results indicated that under static conditions platelets do not significantly increase tumor cell adhesion to either intact ECs or to exposed ECM. Conversely, the studies performed under flow conditions using the flat chamber perfusion system indicated that the presence of 2 × 105 pl/μl in the perfusate significantly increased the number of tumor cells adhered to ECM, and that this effect was shear rate dependent. The maximal values of tumor cell adhesion were obtained, in presence of platelets, at a shear rate of 1,300 sec-1. Furthermore, our results with ASA-treated platelets suggest that the role of platelets in enhancing tumor cell adhesion to ECM is independent of the activation of the platelet cyclooxygenase pathway.

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