scholarly journals CAD Based Analysis for Feasibility of Design of an Amphibious Vehicle for Recreation

2021 ◽  
Vol 10 (10) ◽  
pp. 45-50
Author(s):  
Debashis Majumder* ◽  
◽  
Dr. Anirban Chowdhury ◽  
Keyword(s):  
Fossil Fuel ◽  
Structural Strength ◽  
Maximum Speed ◽  
Surface Shear Stress ◽  
Ansys Software ◽  
Surface Shear ◽  
Marine Life ◽  
Technology Park ◽  
Structural Details ◽  
Negative Effect

An amphibious vehicle is the vehicle that allows occupants to travel on both land and water. Since an amphibious vehicle must inherently possess both land and water capabilities, design of the vehicle should not compromise the requirements for a good boat as well as a good land vehicle. Although, amphibious vehicles were used for different purposes, still there is no mention of application of amphibious vehicle in recreational purposes such as beach riding, surfing on water and travel within Science Parks. Further, with depletion of fossil fuel and for all the negative effect on marine life. Hence, an attempt is made to design an electric amphibious vehicle for recreational purpose and utilize for travel within Science & Technology Park. A conceptual design was worked out and it is matched with visual aspects of amphibian animal like duck. A CAD model was prepared with structural details. Structural strength was analyzed using ANSYS software. CFD analysis was conducted for calculating drag and surface shear stress and buoyancy was calculated. Thus it gives a practical approach to construction of an amphibious vehicle for recreational purpose. The results of the CAD analysis shows that the stress on the Frame was within acceptable limit and the buoyancy conditions are fulfilled. It also suggest for a maximum speed of 40kmph on water. As look and feel of the vehicle inspired from duck beak, it gives expression of amphibian characteristics along with sporty look. Thus, the conceptual vehicle is suitable for use on land and on water inside Science & Technology park.

Detection of viruses by electron microscopy: Increased sensitivity by direct micro-ultracentrifugation of samples

1987 ◽  
Vol 45 ◽  
pp. 908-909
Author(s):  
Alain R. Trudel ◽  
M. Trudel
Keyword(s):  
Electron Microscopy ◽  
Fold Increase ◽  
Observation Time ◽  
Clinical Samples ◽  
Maximum Speed ◽  
Viral Particles ◽  
Structural Details ◽  
Latex Spheres ◽  
Increased Sensitivity ◽  
Size Of Particles

AirfugeR (Beckman) direct ultracentrifugation of viral samples on electron microscopy grids offers a rapid way to concentrate viral particles or subunits and facilitate their detection and study. Using the A-100 fixed angle rotor (30°) with a K factor of 19 at maximum speed (95 000 rpm), samples up to 240 μl can be prepared for electron microscopy observation in a few minutes: observation time is decreased and structural details are highlighted. Using latex spheres to calculate the increase in sensitivity compared to the inverted drop procedure, we obtained a 10 to 40 fold increase in sensitivity depending on the size of particles. This technique also permits quantification of viral particles in samples if an aliquot is mixed with latex spheres of known concentration.Direct ultracentrifugation for electron microscopy can be performed on laboratory samples such as gradient or column fractions, infected cell supernatant, or on clinical samples such as urine, tears, cephalo-rachidian liquid, etc..

Detachment of biofilm bacteria due to variations in nutrient supply

1998 ◽  
Vol 37 (4-5) ◽  
pp. 211-214 ◽  
Author(s):  
Linda K. Sawyer ◽  
Slawomir W. Hermanowicz
Keyword(s):  
Phase Contrast ◽  
Digital Image Analysis ◽  
Specific Growth ◽  
Nutrient Supply ◽  
Surface Shear Stress ◽  
Surface Shear ◽  
Nutrient Limitations ◽  
Contrast Microscopy ◽  
Biofilm Bacteria ◽  
Observable Parameter

Growth and detachment rates of an environmental isolate of Aeromonas hydrophila attached to a surface were determined under varying nutrient supply conditions in a complex medium. Growth and detachment of cells were observed in real time using phase contrast microscopy in glass parallel plate flow chambers. Surface shear stress was controlled in all experiments at 3 N m−2. Images were taken every 15 min. Digital image analysis was used to determine specific growth and detachment rates. An observable parameter proportional to the nutrient depletion at the surface due to transfer limitations was used to indicate nutrient limitations. Specific detachment rates increased as the depletion parameter increased, indicating that nutrient limitations cause this bacterium to detach at greater rates.

Visualization of separation and reattachment in an incident shock-induced interaction

2021 ◽  
pp. 095441002098349
Author(s):  
Yun Jiao ◽  
Chengpeng Wang
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Shear Stress ◽  
Separation Bubble ◽  
Incident Shock ◽  
Incident Shock Wave ◽  
Bottom Wall ◽  
Surface Shear Stress ◽  
Surface Shear ◽  
Oil Flow

An experimental study is conducted on the qualitative visualization of the flow field in separation and reattachment flows induced by an incident shock interaction by several techniques including shear-sensitive liquid crystal coating (SSLCC), oil flow, schlieren, and numerical simulation. The incident shock wave is generated by a wedge in a Mach 2.7 duct flow, where the strength of the interaction is varied from weak to moderate by changing the angle of attack α of the wedge from 8° and 10° to 12°. The stagnation pressure upstream was set to approximately 607.9 kPa. The SSLCC technique was used to visualize the surface flow characteristics and analyze the surface shear stress fields induced by the initial incident shock wave over the bottom wall and sidewall experimentally which resolution is 3500 × 200 pixels, and the numerical simulation was also performed as the supplement for a clearer understanding to the flow field. As a result, surface shear stress over the bottom wall was visualized qualitatively by SSLCC images, and flow features such as separation/reattachment and the variations of position/size of separation bubble with wedge angle were successfully distinguished. Furthermore, analysis of shear stress trend over the bottom wall by a hue value curve indicated that the relative magnitude of shear stress increased significantly downstream of the separation bubble compared with that upstream. The variation trend of shear stress was consistent with the numerical simulation results, and the error of separation position was less than 2 mm. Finally, the three-dimensional schematic of incident shock-induced interaction has been achieved by qualitative summary by multiple techniques, including SSLCC, oil flow, schlieren, and numerical simulation.

Numerical Analysis on Nanofluid Forced Convection in Ducts With Triangular Cross Sections

2011 ◽  
Author(s):  
O. Manca ◽  
S. Nardini ◽  
D. Ricci ◽  
S. Tamburrino
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Forced Convection ◽  
Cross Sections ◽  
Fluid Dynamic ◽  
Pure Water ◽  
Convection Flow ◽  
Uniform Heat Flux ◽  
Surface Shear Stress ◽  
Surface Shear

Heat transfer of fluids is very important to many industrial heating or cooling equipments. Convective heat transfer can be enhanced passively by changing flow geometry, boundary conditions or by enhancing the thermal conductivity of the working fluids. An innovative way of improving the fluid thermal conductivity is to introduce suspended small solid nanoparticles in the base fluids. In this paper a numerical investigation on laminar forced convection flow of a water–Al2O3 nanofluid in a duct having an equilateral triangular cross section is performed. The hydraulic diameter is set equal to 1.0×10−2 m. A constant and uniform heat flux on the external surfaces has been applied and the single-phase model approach has been employed. The analysis has been run in steady state regime for a nanoparticle size equal to 38 nm, considering different volume particle concentrations. The CFD code Fluent has been employed in order to solve the tri-dimensional numerical model. Results are presented in terms of temperature and velocity distributions, surface shear stress and heat transfer convective coefficient, Nusselt number and required pumping power profiles. Comparison with results related to the fluid dynamic and thermal behaviors in pure water are carried out in order to evaluate the enhancement due to the presence of nanoparticles in terms of volumetric concentration.

scholarly journals ESTIMATION OF THE SLIP LENGTH IN THE FLOW OF LIQUID IN MICRO-CHANNELS

2018 ◽  
Vol 40 (2) ◽  
pp. 12-19
Author(s):  
Y.Y. Kovetska
Keyword(s):  
Slip Length ◽  
Slip Flow ◽  
Gas Bubbles ◽  
Hydrophobic Surface ◽  
Dissipative Heating ◽  
Research Review ◽  
Surface Shear Stress ◽  
Surface Shear ◽  
Lower Viscosity ◽  
Micro Channels

Research review of phenomenon for slip flow in micro and nanocannels is presented in the paper. The analysis of theoretical and experimental data characterizing the slip length is carried out. In slip flow in microchannels the slip length is affected by the contact angle of the liquid with the surface, shear stress, pressure, dissipative heating, the amount and nature of the dissolved gas in the liquid, electrical characteristics, surface roughness. Studies of flow in microchannels with hydrophobic walls, which are based on molecular dynamics, showed that the slip length has order of 20 nm. This is much less than the values observed in the experiment. The introduction of an effective (apparent) slip length suggests the existence of a thin layer of gas bubbles near the hydrophobic surface or liquid layer with low value of viscosity and density. Since the idealized model for the total coverage of a hydrophobic surface by gas bubbles gives, as a rule, overestimated values of the slip length in comparison with experimental ones, some researchers consider the inhomogeneous coating of the wall by gas bubbles. In this case, the effect of a layer with a lower viscosity on the slip length turns out to be weaker.

scholarly journals A snow-transport model for complex terrain

1998 ◽  
Vol 44 (148) ◽  
pp. 498-516 ◽  
Author(s):  
Glen E. Liston ◽  
Matthew Sturm
Keyword(s):  
Snow Depth ◽  
Depth Distribution ◽  
Snow Water Equivalent ◽  
Transport Model ◽  
Vegetation Type ◽  
Cold Season ◽  
Snow Accumulation ◽  
Surface Shear Stress ◽  
Surface Shear ◽  
Snow Transport

AbstractAs part of the winter environment in middle- and high-latitude regions, the interactions between wind, vegetation, topography and snowfall produce snow covers of non-uniform depth and snow water-equivalent distribution. A physically based numerical snow-transport model (SnowTran-3D) is developed and used to simulate this three-dimensional snow-depth evolution over topographically variable terrain. The mass-transport model includes processes related to vegetation snow-holding capacity, topographic modification of wind speeds, snow-cover shear strength, wind-induced surface-shear stress, snow transport resulting from saltation and suspension, snow accumulation and erosion, and sublimation of the blowing and drifting snow. The model simulates the cold-season evolution of snow-depth distribution when forced with inputs of vegetation type and topography, and atmospheric foreings of air temperature, humidity, wind speed and direction, and precipitation. Model outputs include the spatial and temporal evolution of snow depth resulting from variations in precipitation, saltation and suspension transport, and sublimation. Using 4 years of snow-depth distribution observations from the foothills north of the Brooks Range in Arctic Alaska, the model is found to simulate closely the observed snow-depth distribution patterns and the interannual variability.

Measurement of surface shear stress vectors using liquid crystal coatings

AIAA Journal ◽  
1994 ◽  
Vol 32 (8) ◽  
pp. 1576-1582 ◽  
Author(s):  
Daniel C. Reda ◽  
Joseph J. Muratore
Keyword(s):  
Shear Stress ◽  
Liquid Crystal ◽  
Surface Shear Stress ◽  
Surface Shear

Seismic interpretation theory for an elastic earth

1954 ◽  
Vol 224 (1156) ◽  
pp. 43-63 ◽  
Keyword(s):  
Shear Stress ◽  
Seismic Interpretation ◽  
Elastic Theory ◽  
Static Case ◽  
Surface Shear Stress ◽  
Elastic Parameters ◽  
Surface Shear ◽  
Special Cases ◽  
Present Solution ◽  
Ray Path

The seismic interpretation problem for an isotropic spherical earth is analyzed on the basis of elastic theory, under the assumption that the three independent elastic parameters are unknown continuous functions of the depth. It is shown that solutions for these functions may be obtained in the form of Taylor’s series. The problem is treated for three types of symmetrical excitation conditions on the free surface: (1) a shear source of type p rϕ only; (2) a pressure distribution with vanishing surface shear stress; (3) an excitation consisting of pressure in combination with surface shear stress of type p rθ . In each case the excitation functions are arbitrary functions of time. It is assumed that the associated components of surface displacement over the sphere are known from available observations, as functions of time. Thus, the complete information contained in seismic records is used in the proposed interpretation process, without need of selecting, identifying and assigning arrival times to specific events on the records. The two static elastic parameters may theoretically be determined from observations at a single frequency, including the frequency zero, or static case. The determination of the dynamic elastic parameter requires the use of at least two frequencies. Algebraic checks are obtained by comparing the general solutions with the corresponding results for two special cases in which the elastic parameters vary in a prescribed manner in the interior of the sphere. In both these cases treatment by the classical ray-path method of interpretation is excluded, because the wave velocity decreases with depth. Furthermore, the ray-path method (which is essentially a method of geometrical optics) would fail to distinguish between the two examples in any case, since the velocity function is the same in both, although the elastic parameters differ. In contrast to the valuable ray-path method, the analytical procedures in the present solution of the elastic problem are prohibitively cumbersome. Practical application of elastic theory to the direct interpretation of seismograms requires further development of the theory with probable utilization of modern high-speed computing methods.

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