Influence of Sediment Disturbance and Water Flow on the Growth of the Soft-Shell Clam,Mya arenariaL.

1990 ◽  
Vol 47 (9) ◽  
pp. 1655-1663 ◽  
Author(s):  
Craig W. Emerson
Keyword(s):  
Water Flow ◽  
Growth Rates ◽  
Free Stream ◽  
Maximum Growth ◽  
Coastal Development ◽  
Low Flow ◽  
Stream Velocity ◽  
Soft Shell Clam ◽  
Sediment Disturbance ◽  
Soft Shell

The importance of sediment disturbance and water flow to the production of the soft-shell clam, Mya arenaria, was assessed in laboratory flumes by measuring growth rates of clams exposed to a gradation of bed shear stress, free-stream velocity, and frequency and depth of sediment disturbance over a 10-m period. In the absence of sediment disturbance, growth of soft-tissue was directly proportional to both free-stream (U) and shear (U*) velocity (r2 = 0.64 and 0.72, respectively). It was suggested that increased organic seston flux linked higher water flow to higher growth. In all treatments, maximum growth rates were observed with daily disturbance of the top centimeter of sediment. No level of disturbance resulted in growth rates lower than those of undisturbed clams in low flow (U = 0.4 cm∙s−1, U* = 0.1 cm∙s−1). The stimulation of growth under maximum sediment disturbance was removed when U exceeded ~3 cm∙s−1(U* = 0.7 cm∙s−1). An energy budget for M. arenaria indicated that the amount of organic material suspended during sediment disturbance was insufficient to account for the increased growth in clams subjected to high levels of disturbance. It was suggested that the sediment disturbance associated with intense clam harvesting, and changes in local hydrography resulting from coastal development, may be responsible for some of the unexplained growth variation in commercial clam stocks.

The Effect of Water Flow Rate Upon the Environmentally Assisted Cracking Response of a Low-Alloy Steel: Experimental Results Plus Modeling

1997 ◽  
Vol 119 (1) ◽  
pp. 83-90 ◽  
Author(s):  
L. A. James ◽  
H. B. Lee ◽  
G. L. Wire
Keyword(s):  
Water Flow ◽  
Free Stream ◽  
Critical Concentration ◽  
Water Flow Rate ◽  
Crack Tip ◽  
Computer Code ◽  
Stream Velocity ◽  
Low Alloy Steels ◽  
Ion Migration ◽  
Environmentally Assisted Cracking

The presence of a critical concentration of sulfides at the tip of a crack is thought to be a prerequisite for environmentally assisted cracking (EAC) in low-alloy steels. Sulfides can be “supplied” to the crack tip by a growing crack intersecting and dissolving embedded MnS inclusions present in the steel as an impurity. Sulfides can be removed from the crack tip by diffusion, ion migration, fatigue pumping, or convection induced within the crack by external water flow. EAC can result when the supply of sulfides exceeds the loss by mass transport. This paper presents results of experiments conducted on relatively large semi-elliptical surface cracks subjected to mean free stream velocities of 0.56, 1.71, and 5.00 m/s. The two higher velocities resulted in mitigation of EAC, while the lowest did not. A computational fluid dynamics computer code, FIDAP®, was employed to model the interaction between the flow within the crack cavity and the free stream flow. The model demonstrated that the two highest free stream velocities produced a significant interaction between the two regimes, but that the lowest free stream velocity produced minimal interaction. Thus, there was good qualitative agreement between the experimental and analytical results.

Southern limit of distribution of the soft-shell clam Mya arenaria on the Atlantic East Coast

2009 ◽  
Vol 12 (3) ◽  
pp. 429-432 ◽  
Author(s):  
Anxo Conde ◽  
Júlio Novais ◽  
Jorge Domínguez
Keyword(s):  
East Coast ◽  
Mya Arenaria ◽  
Southern Limit ◽  
Soft Shell Clam ◽  
Soft Shell

Effects of Embedded Vortices on Film-Cooled Turbulent Boundary Layers

1989 ◽  
Vol 111 (1) ◽  
pp. 71-77 ◽  
Author(s):  
P. M. Ligrani ◽  
A. Ortiz ◽  
S. L. Joseph ◽  
D. L. Evans
Keyword(s):  
Heat Transfer ◽  
Boundary Layers ◽  
Film Cooling ◽  
Free Stream ◽  
Flow Behavior ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Turbulent Boundary Layers ◽  
Stream Velocity ◽  
Longitudinal Vortices

Heat transfer effects of longitudinal vortices embedded within film-cooled turbulent boundary layers on a flat plate were examined for free-stream velocities of 10 m/s and 15 m/s. A single row of film-cooling holes was employed with blowing ratios ranging from 0.47 to 0.98. Moderate-strength vortices were used with circulating-to-free stream velocity ratios of −0.95 to −1.10 cm. Spatially resolved heat transfer measurements from a constant heat flux surface show that film coolant is greatly disturbed and that local Stanton numbers are altered significantly by embedded longitudinal vortices. Near the downwash side of the vortex, heat transfer is augmented, vortex effects dominate flow behavior, and the protection from film cooling is minimized. Near the upwash side of the vortex, coolant is pushed to the side of the vortex, locally increasing the protection provided by film cooling. In addition, local heat transfer distributions change significantly as the spanwise location of the vortex is changed relative to film-cooling hole locations.

scholarly journals Modeling of Piezoelectric Energy Harvesting from Freely Oscillating Cylinders in Water Flow

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Min Zhang ◽  
YingZheng Liu ◽  
ZhaoMin Cao
Keyword(s):  
Energy Harvesting ◽  
Free Stream ◽  
Piezoelectric Materials ◽  
Load Resistance ◽  
Stream Velocity ◽  
Piezoelectric Energy Harvesting ◽  
Vibratory System ◽  
System Parameters ◽  
Piezoelectric Energy ◽  
Vortex Induced Vibrations

A concept of energy harvesting from vortex-induced vibrations of a rigid circular cylinder with two piezoelectric beams attached is investigated. The variations of the power levels with the free stream velocity are determined. A mathematical approach including the coupled cylinder motion and harvested voltage is presented. The effects of the load resistance, piezoelectric materials, and circuit combined on the natural frequency and damping of the vibratory system are determined by performing a linear analysis. The dynamic response of the cylinder and harvested energy are investigated. The results show that the harvested level in SS and SP&PS modes is the same with different values of load resistance. For four different system parameters, the results show that the bigger size of cylinder with PZT beams can obtain the higher harvested power.

Reassessment of Maximum Growth Rates for C3 and C4 Crops

1978 ◽  
Vol 14 (1) ◽  
pp. 1-5 ◽  
Author(s):  
J. L. Monteith
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Growing Season ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Crop Growth ◽  
Close Inspection ◽  
Similar Difference ◽  
Photosynthetic Efficiencies

SUMMARYFigures for maximum crop growth rates, reviewed by Gifford (1974), suggest that the productivity of C3 and C4 species is almost indistinguishable. However, close inspection of these figures at source and correspondence with several authors revealed a number of errors. When all unreliable figures were discarded, the maximum growth rate for C3 stands fell in the range 34–39 g m−2 d−1 compared with 50–54 g m−2 d−1 for C4 stands. Maximum growth rates averaged over the whole growing season showed a similar difference: 13 g m−2 d−1 for C3 and 22 g m−2 d−1 for C4. These figures correspond to photosynthetic efficiencies of approximately 1·4 and 2·0%.

scholarly journals Added mass of a circular cylinder oscillating in a free stream

2013 ◽  
Vol 469 (2156) ◽  
pp. 20130135 ◽  
Author(s):  
Efstathios Konstantinidis
Keyword(s):  
Circular Cylinder ◽  
Free Stream ◽  
Transverse Velocity ◽  
Inertial Force ◽  
Added Mass ◽  
Stream Velocity ◽  
Virtual Experiment ◽  
Classical Formulation ◽  
Fundamental Understanding ◽  
Two Dimensional Flow

The fundamental understanding of the added mass phenomenon associated with the motion of a solid body relative to a fluid is revisited. This paper focuses on the two-dimensional flow around a circular cylinder oscillating transversely in a free stream. A virtual experiment reveals that the classical approach to this problem leads to a paradox. The inertial force is derived afresh based on analysis of the motion in a frame of reference attached to the cylinder centroid, which overcomes the paradox in the classical formulation. It is shown that the inertial force depends not only on the acceleration of the cylinder per se , but also on the relative motion between body and fluid embodied in a parameter called alpha, α , which represents the ratio of the maximum transverse velocity of the cylinder to the free-stream velocity; the induced inertial force is directionally varying and non-harmonic in time depended on the alpha parameter. It is further shown that the component of the inertial force in the transverse direction is negligible for α <0.1, increases quadratically for α <0.5, and tends asymptotically to the classical result as , i.e. in still fluid.

A tumor on the siphons of a soft-shell clam, Mya arenaria

1968 ◽  
Vol 11 (3) ◽  
pp. 504-506 ◽  
Author(s):  
Gilbert B. Pauley ◽  
Thomas C. Cheng
Keyword(s):  
Mya Arenaria ◽  
Soft Shell Clam ◽  
Soft Shell
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