scholarly journals SCALE LAWS FOR BED FORMS IN LABORATORY WAVE MODELS

1974 ◽  
Vol 1 (14) ◽  
pp. 62
Author(s):  
G.R. Mogridge
Keyword(s):  
Experimental Study ◽  
Wave Action ◽  
Water Tunnel ◽  
Wave Flume ◽  
Wide Range ◽  
Bed Forms ◽  
Wave Models

An experimental study of the variables governing the development of bed forms under wave action has been conducted. A wide range of conditions was covered by the use of a wave flume and an oscillating water tunnel. Scale laws for modelling bed forms are developed using the results of these experiments. It is recommended that the model sediment used should be the same density as in the prototype and its size should be scaled geometrically. If this is not practical, it is shown how the scale laws can be used to minimise the distortion of the bed forms produced in the model.

scholarly journals EXPERIMENTS ON BED FORM GENERATION BY WAVE ACTION

1972 ◽  
Vol 1 (13) ◽  
pp. 57 ◽  
Author(s):  
G.R. Mogridge ◽  
J.W. Kamphuis
Keyword(s):  
Specific Gravity ◽  
Wave Action ◽  
Water Tunnel ◽  
Oscillatory Flows ◽  
Wave Flume ◽  
Form Generation ◽  
Sediment Bed ◽  
Wide Range ◽  
Bed Forms ◽  
Bed Form

Experiments to determine the length, height and steepness of bed forms generated by wave action have been conducted in a laboratory wave flume and an oscillating water tunnel. The effects of a wide range of oscillatory flows were examined on polystyrene (specific gravity 1.05, diameter 1.54 mms), bakelite (specific gravity 1.60, diameter 0.52 mms), bakelite (specific gravity 1.51, diameter 0.67 mms) and sand (specific gravity 2.68, diameter 0.36 mms). From the results of the experiments design curves were plotted which make it possible to predict the length and height of bed form that will develop on any specified sediment bed for given conditions of fluid oscillation.

Patterns in diversity and composition of the microbenthos of subarctic intertidal beaches with different morphodynamics

2020 ◽  
Vol 648 ◽  
pp. 19-38
Author(s):  
AI Azovsky ◽  
YA Mazei ◽  
MA Saburova ◽  
PV Sapozhnikov
Keyword(s):  
Species Abundance ◽  
Abundance Ratio ◽  
Wave Action ◽  
Coarse Grained ◽  
Sediment Properties ◽  
Β Diversity ◽  
Α Diversity ◽  
Wide Range ◽  
Similar Mode ◽  
Abundance And Diversity

Diversity and composition of benthic diatom algae and ciliates were studied at several beaches along the White and Barents seas: from highly exposed, reflective beaches with coarse-grained sands to sheltered, dissipative silty-sandy flats. For diatoms, the epipelic to epipsammic species abundance ratio was significantly correlated with the beach index and mean particle size, while neither α-diversity measures nor mean cell length were related to beach properties. In contrast, most of the characteristics of ciliate assemblages (diversity, total abundance and biomass, mean individual weight and percentage of karyorelictids) demonstrated a strong correlation to beach properties, remaining low at exposed beaches but increasing sharply in more sheltered conditions. β-diversity did not correlate with beach properties for either diatoms or ciliates. We suggest that wave action and sediment properties are the main drivers controlling the diversity and composition of the intertidal microbenthos. Diatoms and ciliates, however, demonstrated divergent response to these factors. Epipelic and epipsammic diatoms exhibited 2 different strategies to adapt to their environments and therefore were complementarily distributed along the environmental gradient and compensated for each other in diversity. Most ciliates demonstrated a similar mode of habitat selection but differed in their degree of tolerance. Euryporal (including mesoporal) species were relatively tolerant to wave action and therefore occurred under a wide range of beach conditions, though their abundance and diversity were highest in fine, relatively stable sediments on sheltered beaches, whereas the specific interstitial (i.e. genuine microporal) species were mostly restricted to only these habitats.

scholarly journals MAGNITUDE OF THE B-FACTOR UNDER WAVE ACTION

1986 ◽  
Vol 1 (20) ◽  
pp. 67
Author(s):  
J. Van de Graaff ◽  
R.C. Steijn
Keyword(s):  
Velocity Distribution ◽  
Water Depth ◽  
Sediment Concentration ◽  
Wave Action ◽  
Practical Applications ◽  
Wave Flume ◽  
Sediment Size ◽  
Flume Tests ◽  
Waves And Currents ◽  
The Moment

The sediment transport due to waves and currents depends on the distribution of sediment concentration and on the distribution of the velocity over the water depth. Our knowledge of both phenomena for practical applications is still rather poor. Some results of wave flume tests concerning the distribution of sediment concentrations due to wave action will be discussed. It turns out that the sediment size of the bottom material has a rather unexpected effect hereupon. With respect to the velocity distribution only some qualitative remarks can be made at the moment.

scholarly journals Improvement of Pump Performance at Off-Design Conditions

1985 ◽  
Author(s):  
J. Paulon ◽  
C. Fradin ◽  
J. Poulain
Keyword(s):  
Experimental Study ◽  
Flow Field ◽  
Mass Flow ◽  
Flow Characteristic ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Pump Performance ◽  
Wide Range ◽  
Mass Flows ◽  
Design Value

Industrial pumps are generally used in a wide range of operating conditions from almost zero mass flow to mass flows larger than the design value. It has been often noted that the head-mass flow characteristic, at constant speed, presents a negative bump as the mass flow is somewhat smaller than the design mass flows. Flow and mechanical instabilities appear, which are unsafe for the facility. An experimental study has been undertaken in order to analyze and if possible to palliate these difficulties. A detailed flow analyzis has shown strong three dimensional effects and flow separations. From this better knowledge of the flow field, a particular device was designed and a strong attenuation of the negative bump was obtained.

scholarly journals Strength Comparison of FDM 3D Printed PLA Made by Different Manufacturers

TEM Journal ◽  
2020 ◽  
pp. 966-970
Author(s):  
Damir Hodžić ◽  
Adi Pandžić ◽  
Ismar Hajro ◽  
Petar Tasić
Keyword(s):  
Experimental Study ◽  
Additive Manufacturing ◽  
Fused Deposition Modelling ◽  
Fused Deposition ◽  
Manufacturing Technique ◽  
Plastic Materials ◽  
Wide Range ◽  
3D Printed ◽  
The Difference ◽  
Printing Parameters

Widely used additive manufacturing technique for plastic materials is Fused Deposition Modelling (FDM). The FDM technology has gained interest in industry for a wide range of applications, especially today when large number of different materials on the market are available. There are many different manufacturers for the same FDM material where the difference in price goes up to 50%. This experimental study investigates possible difference in strength of the 3D printed PLA material of five different manufacturers. All specimens are 3D printed on Ultimaker S5 printer with the same printing parameters, and they are all the same colour.

scholarly journals Experimental study of immersion ratio and shaft inclination angle in the performance of a surface-piercing propeller

2019 ◽  
Vol 10 (1) ◽  
pp. 153-167
Author(s):  
Seyyed Mostafa Seyyedi ◽  
Rouzbeh Shafaghat ◽  
Mohioddin Siavoshian
Keyword(s):  
Experimental Study ◽  
Free Surface ◽  
Surface Water ◽  
Inclination Angle ◽  
Superior Performance ◽  
Design Parameters ◽  
Water Tunnel ◽  
Hydrodynamic Coefficients ◽  
Thrust And Torque ◽  
Surface Piercing Propeller

Abstract. Surface-piercing propellers have been widely used in light and high-speed vessels because of their superior performance. Experimental study of these propellers is one of the most reliable and accurate ways which can provide details about the performance and effect of different design parameters on the performance of the surface-piercing propellers. In this research, a five-blade surface-piercing propeller was tested in the free surface water tunnel of Babol Noshirvani University of Technology in order to expand the available experimental data and database for future engineering designs. The effects of immersion ratio and shaft inclination angle on the propeller's efficiency and hydrodynamic coefficients were examined. A free surface water tunnel and a calibrated dynamometer with the measurability of the thrust forces and the torque of a propeller were used for this purpose. Comparing the obtained results with the existing semi-experimental equations shows that the equations presented in various geometric conditions are not accurate enough, and developing the existing database is necessary. The details of the obtained results showed that the hydrodynamic coefficients of the thrust and torque increased by increasing the immersion ratio, but the coefficient of hydrodynamic thrust and efficiency reduced. The results also indicated that the coefficient of torque increased by increasing the shaft inclination angle. The highest efficiency of the propeller was achieved in the range of 40 %–50 % immersion ratios at all angles of shaft inclination. For all immersion ratios, the maximum and minimum efficiencies were obtained at 0 and 15 shaft inclination angles, respectively. The best efficiency of the propeller was at 50 % immersion ratio and zero shaft inclination angle.

A Theoretical and Experimental Study on the Planform of Superventilated Wings

1974 ◽  
Vol 18 (03) ◽  
pp. 169-184
Author(s):  
L. F. Tsen ◽  
M. Guilbaud
Keyword(s):  
Experimental Study ◽  
Aspect Ratio ◽  
Numerical Method ◽  
Lower Surface ◽  
Cavitation Number ◽  
Water Tunnel ◽  
Surface Theory ◽  
Lifting Surface ◽  
Measured Force

This study explores the influence of the aspect ratio, the taper ratio, and the sweepback on the flow over trapezoidal superventilated wings with a flat wetted lower surface. The flow is first calculated by a numerical method in the scope of the linearized supercavitating lifting-surface theory. The calculated wings are then made and tested in a water tunnel at zero cavitation number. The measured force and moment coefficients are compared with the prediction.

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