Single Fin Research Articles

The Kirchhoff Transformation for Convective-radiative Thermal Problemsin Fins

- The present work describes the thermal profile of a single dissipation fin, where their surfaces reject heat to the environment. The problem happens in steady state, which is, all the analysis occurs after the thermal distribution reach heat balance considering that the fin dissipates heat by conduction, convection and thermal radiation. Neumann and Dirichlet boundary conditions are established, characterizing that heat dissipation occurs only on the fin faces, in addition to predicting that the ambient temperature is homogeneous. Heat transfer analysis is performed by computational simulations using appropriate numerical methods. The most of solutions in the literature consider some simplifications as constant thermal conductivity and linear boundary conditions, this work addresses this subject. The method applied is the Kirchhoff Transformation, that uses the thermal conductivity variation to define the temperatures values, once the thermal conductivity variate as a temperature function. For the real situation approximation, this work appropriated the silicon as the fin material to consider the temperature function at each point, which makes the equation that governs the non-linear problem. Finally, the comparison of the results obtained with typical results proves that the assumptions of variable thermal conductivity and heat dissipation by thermal radiation are crucial to obtain results that are closer to reality.

A method to predict the torsional resistance of suction caisson with anti-rotation fins in clay

Suction caisson foundations have been increasingly employed as a primary solution to support the offshore fixed- or mobile-structures. Due to harsh environment and complex force transferring of offshore structures, they are still being developed as to satisfy increasing requirements in strict working scenarios. One of emerging challenges is a torsion-governing failure, which has been observed in the oil and gas industry (i.e. significant multiple-inline-force-induced torsion) and in the renewable energy field (i.e. non-coplanar tensile force induced torsion). This paper introduces a novel suction caisson foundation, with anti-rotational fins assembled on the outer skin of caisson. By a comprehensive numerical study, the evolution from local to global failure as the fin numbers from single to multiple, is examined in the clayey soil deposit with effects of soil strength heterogeneity, fins dimension, installation process and foundation-soil interface considered. Based on these, a set of methods to estimate the ultimate torsional capacity of such novel caisson is proposed, which starts from the gain in capacity for a single fin, and evaluate the changes of gains in capacity as fin numbers, then identify the optimised anti-rotational capacity. Finally, three key parameters (i.e. the required fin numbers, the available anti-rotational capacity and the optimised anti-rotational capacity) with some critical considerations, recommendations and implications have been concluded for design practice.

Detailed CFD simulations of pure substance condensation on horizontal annular low finned tubes including a parameter study of the fin slope

The use of annular low-finned tubes in tube bundle condensers greatly increases the efficiency. This enables enhanced heat coupling within chemical plants, reducing the overall CO2 emission and power consumption. Due to the complex geometry of these tubes, no generalized condensation model is present so far. In this study, we use highly resolved computational fluid dynamics simulations to investigate pure substance condensation on said tubes with a condensation model which is independent of empirical parameters. Within these simulations, the condensate film is fully resolved and heat transfer coefficients are calculated providing the complete information about the condensation process on annular low-finned tubes for the first time. Additionally, a parameter study for the incline of the annular fin is provided. Therefore, computational fluid dynamics is used to predictively evaluate the influence of a single fin parameter, the incline of the fin, of annular low-finned tubes, for the first time. The simulations provide information about the film thickness along the fin flank and the flooding behavior of the tubes. An accurate fluid dynamic behavior of the two-phase flow is gained. Furthermore, the resulting heat transfer coefficients stand in excellent agreement to experimental data.

An efficient method to assess effect of fin on the course stability of towing system

Some new-built ship-shaped offshore structures like FPSO or FPU are found to show insufficient course stability due to rough design, which makes the towing operation hazardous. This paper aims at investigating the stern fin as a proposed solution for improving the poor course stability of a FPSO in towing operation by creating a practical approach. The fin’s hydrodynamic lift coefficient is predicted by the vortex lattice method. The numerical towing system is of three degrees of freedoms and accounts for hydrodynamic forces, the interactions acting on the hull and other appendages, as well as the towing line. Various hydrodynamic derivatives are considered linear and estimated by the empirical method. The configurations of single fin, double fins, and twin fins, as well as the influence on towing stability, are studied. In particular, the hydrodynamic interaction of twin fins, lift coefficient reduction and the impact of spacing are analysed. Different stable and unstable behaviours in the time domain are observed and discussed in depth. The eigenvalue analysis is conducted based on the linearized towing system.

Effect of Fin Length and Location on Natural Convection Heat Transfer in a Wavy Cavity

The present study aims to analyze the natural convection flow and heat transfer in a wavy cavity with a single horizontal fin attached to its hot wall. Galerkin weighted residual finite element technique has been employed to solve the governing nonlinear dimensionless equations. The effects of model parameters like Rayleigh number, fin length and location on the fluid flow and heat transfer are investigated. The obtained results are exhibited graphically in terms of flow structure, temperature dispersion, velocity field, fin effectiveness, local Nusselt number, and average Nusselt number. It is observed that the different fin length and location have a substantial effect on flow structure and temperature field. Fin effectiveness is also studied and the highest fin effectiveness was found at fin length (L = 0.75). Besides, it is also found that the mean Nusselt number increases significantly with the increase of Rayleigh number and fin length. Wavy cavity becomes more effective on heat transfer behaviors and fluid flow than that of a square cavity.

Unsteady natural convection of water adjacent to the sidewall of a differentially heated cavity with multiple fins

The unsteady thermal flow and heat transfer adjacent to the sidewall of a differentially heated cavity with single and multiple nonconductive fins are investigated utilizing the finite element method. The transition to the unsteady flow, as well as flow oscillations, is described for the water-filled cavity and Rayleigh numbers ranging from 1 × 107 to 1 × 1010, including the critical Rayleigh number. Characteristics of unsteady flows are investigated for early, transitional, and quasi-steady stages. For all cases, heat transfer from the finned sidewall to the interior fluid is quantified and compared with the cavity without the fin. Results show that the volumetric flow rate along the vertical axis in the middle of the cavity rises by increasing the number of fins (up to 13.41% for the cavity with two fins for Ra = 1.84 × 109) in transitional and quasi-steady stages. Moreover, the increment of fin number and Ra leads to a higher enhancement factor (ε) that shows the heat transfer enhancement or depression. For Ra = 1.84 × 109, the maximum ε for the cavity with one and three fins is calculated about 17.5% and 34% respectively.

Cooperative Optimal Collision Avoidance Laws for a Hybrid-Tailed Robotic Fish

This brief addresses the problem of collision avoidance by robotic fish that have a single caudal fin. The fish is hybrid-tailed in that the caudal fin is driven by a double-jointed mechanism. One joint is driven by a servomotor and the second joint is driven by an ionic polymer-metal composite (IPMC) actuator, which is often called an artificial muscle. For this type of robotic fish, collision avoidance is performed by employing a collision cone approach. Within the framework of the collision cone approach, Lyapunov-based methods are employed to determine analytical expressions of nonlinear guidance laws with which cooperative collision avoidance can be achieved. It is shown how these cooperative collision avoidance laws can be made optimal in the sense of minimizing an energy-like performance index. The conditions under which the developed guidance laws are robust to sensor measurement errors are determined. Simulations and experiments are performed to validate the guidance laws.

Graph Theory-Based Mathematical Calculation Modeling for Temperature Distribution of LED Lights’ Convective Cooled Heat Sinks under Moisture Environment

In this paper, a mathematical model based on graph theory is proposed to calculate the heat distribution of LED lights’ convective cooled heat sink. First, the heat and mass transfer process of a single fin under moisture environment is analyzed. Then, the heat transfer process is characterized by a digraph, defining fins and joints of a heat sink as edges and vertices in graph theory. Finally, the whole heat transfer process is described by two criteria achieved based on graph theory. Therefore, the temperature-heat calculation equations of the whole heat sink are deduced. The accuracy of this model is verified by testing the junction temperature of different LED chips mounted on the same heat sink under moisture environment, and the relative errors between the calculated value and the experimental data are all within 5%, and it is also concluded from the model that heat sinks with an identical heat digraph but different types have close cooling performance and are verified by two typical heat sinks, cylindrical heat sink and rectangular plate-fin heat sink, under the same conditions. The mathematical model based on group theory developed in this paper combined with computer technology is convenient for the performance analysis among a large number of heat sink fin arrangement schemes.

The simulation of single wraparound fin on a semi-cylindrical missile body

PurposeThe purpose of this paper is to establish a freestream computational fluid dynamics (CFD) model of a three-dimensional non-spinning semi-cylindrical missile model with a single wrap around fin in Mach 2.70-3.00M range and 0° angle of attack, and ultimately establishing itself for future research study.Design/methodology/approachIn this study, the behaviour of flow around the fin was investigated using a κ-ϵ turbulence model of second-order of discretization. This was done using a highly structured mesh. Additionally, an inviscid CFD simulation involving the same boundary conditions have also been carried out for comparison.FindingsThe obtained values of aerodynamic coefficients and pressure contours visualizations are compared against their experimental and computational counterparts. A typical missile aerodynamic characteristic trend can be seen in the current CFD.Practical implicationsThe predicted values of the aerodynamic coefficients of this single fin model have also been compared to those of the full missile body comprising of four fins from the previous research studies, and a similar aerodynamic trend can be seen.Originality/valueThis study explores the possibility of the use of turbulence modelling in a single fin model of a missile and provides a basic computational model for further understanding the flow behaviour near the fin.

Investigation of flow-field around a single generic planar fin using CFD

The purpose of this paper is to initiate a 3-D non-spinning semi-circular missile model with a single generic planar fin and perform a computational analysis on it to understand the flow pattern around the fin. A freestream computational fluid dynamics analysis was done in the subsonic and supersonic Mach range, in which, the fluid behaviour was investigated using a two-equation turbulence model. A structured mesh was adopted to visualize the flow pattern around the fin. The aerodynamic coefficients were calculated for the model, and the predicted values were compared with the previous experimental results as well as the numerical results. This paper attempts to present all the possible flow visualizations which might help in better understanding of flow around missiles having planar fins. This work also attempts to establish a turbulent computational model for a single planar fin missile model for subsonic to supersonic range.

Experimental determination of circular fin effectiveness

The flow and heat transfer at the surface of a single circular fin and a finned cylinder were investigated comprehensively. The technique was carried out by combining PIV (Particle Image Velocimetry), gradient heat flux measurement and thermometry. The experiments were performed for a hollow (isothermal) fin and a fin made of titanium alloy VT22. The fins with a height of 20 and 60 mm were alternately mounted on a hollow cylinder. The cylinder was heated by saturated water vapor at atmospheric pressure. The angling device allowed us to investigate both the cross and non-cross flows around the model. The yaw angle β was 5, 10 and 15°. Visualization of the flow and measurement of the heat flux per unit area was carried out separately and independently in the same experiment. The PIV results revealed the influence of the yaw angle and intercostal space on the flow between the fins. Gradient heat flux sensors made it possible to obtain a distribution of the heat flux per unit area. Then the local heat transfer coefficients were calculated using thermometry data. It was possible to determine experimentally the effectiveness of the circular fins. This approach opens up new opportunities for study of convective heat transfer at surfaces of various shapes and purposes.

Embryonic and larval traits of the temperate damselfish Chromis crusma reveal important similarities with other Pomacentridae throughout the family's thermal range.

Embryonic development and larval morphology of Chromis crusma was described from five nests sampled between 21 and 25 m depth in central Chile (33°S). From each nest, a set of c. 100 randomly selected eggs were hand-collected and transported in seawater to the laboratory. Subsets of c. 30 eggs per nest were maintained in 50 ml glass containers at a constant ambient temperature of c. 12°C (range 11.5-12.9°C). Egg length (L) and width (W) and larval notochordal length (LN ) were measured from photographs. Geometric morphometric analyses were performed in newly hatched and 1 week old larvae to quantify shape changes. Ellipsoid eggs had an average (mean ± SE) size of 1.12 ± 0.05 mm L and 0.67 ± 0.02 mm W, with volume being similar throughout 15 developmental stages (i.e., ellipsoid-shaped; 0.27 mm3 ). Planktonic larvae hatched between 5 and 11 days at 12°C and had a mean LN of 3.13 ± 0.25 mm, a yolk sack volume of 0.03 mm3 and an oil droplet volume of 0.005 mm3 . Morphological traits at hatching included: (a) lack of paired fins and jaws; (b) single medial fin fold; (c) lack of eye pigmentation; (d) yolk sac present near anterior tip; (e) melanophores distributed along ventral surface with one pair over the forehead. In order to generate an up-to-date summary of developmental traits within Pomacentridae, we reviewed literature on egg development (e.g., shape and number of oil droplets), hatching and larval traits (e.g., morphology, pigmentation patterns). Thirty-two publications accounting for 35 species were selected, where eggs, embryonic development, hatching and larval traits were found for 26, 21, 24 and 34 species, respectively. In order to evaluate potential phylogenetic and environmental relationships within the early stages of Pomacentridae, cluster analyses (Bray Curtis similarity, group average) were also performed on egg and larval traits of 22 species divided by subfamily (Stegastinae, Chrominae, Abudefdufinae, Pomacentrinae) and thermal ranges (i.e., low: 16.5°C (range: 12-21°C), medium: 24.5°C (range:21-28°C) and high: 27°C (range: 26-28°C)), suggesting that early developmental patterns can be segregated by both temperature and phylogenetic relationships.

Performance of vertical axis Savonius wind turbines related to the fin number on the blade

Model and the number of blades on the wind turbine greatly affect its performance. The purpose of this research is to know the effect of the fin on Savonius turbine U type 4 number blade. Simulation using Solidworks (Flow Simulation) software based on Finite Element Analysis (FEA) Method, will show pressure distribution and velocity distribution of blade rotor savonius wind turbines. The simulations to compare on the variation of the addition of 1 fin, 2 fins, and blade without fin (standard). The wind speed variations applied to each of the blades is 5 m/s, and 7 m/s respectively. The simulation results showed that the performance of pressure distribution and velocity distribution on each blade is higher and more widespread and evenly distributed, occurring on each blade with the addition of two fins compared to a single fin turbine and standard blade (without the addition of fin). The higher wind speed applied to the turbine blades will have a significant effect on the value of pressure distribution and velocity distribution on the blade. The effectiveness of pressure distributions and velocity distributions that occurs on the turbine blades will be significant to effect for the rotation on the turbine shaft, so as to have a significant impact on the performance the turbines.

Numerical Investigation of Natural Convection Flow in a Hexagonal Enclosure Having Vertical Fin

Numerical study of natural convection flow in a hexagonal enclosure with a single vertical fin attached to its heated bottom wall has been carried out. Finite element method based Galerkin weighted residual technique is used to solve the governing equation. The horizontal walls of the enclosure are kept at constant high temperature while the inclined walls are kept at constant cold temperature. A vertical heated fin is attached to the hot bottom wall with a length at a position from the left surface having thickness . The Prandlt number for the flow inside the enclosure is 0.71. The results of the problem are presented in graphical and tabular forms and discussed. The fin efficiency and temperature distribution were examined. The numerical results indicate the strong influence of the mentioned parameters on the flow structure and heat transfer as well as temperature. A set of graphical results are presented in terms of streamlines, isotherms contour, temperature profiles, velocity profiles, local Nusselt number and average Nusselt number. The obtained results indicated that the heat transfer rate increases with the increase of Rayleigh number in a hexagonal enclosure. The results are validated comparing with the published works.

Electrical Characteristics of n-Type FinFETs Under <inline-formula> <tex-math notation="LaTeX">$V_{T}$ </tex-math> </inline-formula> Ion Implantation on SOI Substrate

The electrical characteristics of single Si-fin n-type fin field-effect transistors at the threshold voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> ) implantation energy 6 and 10 keV in the experimental work were practically extracted and analyzed. In general, the electrical performance of the tested devices at the lower implantation energy shows a better performance than the other group such as in drive current, subthreshold swing, punchthrough voltage, and drain-induced barrier lowering, especially as the feature size of these devices gets smaller up to 17 nm of channel width. However, the channel mobility in transconductance view at the higher implantation energy is better due to the smaller channel scattering.

Numerical study of heat transfer in rectangular channels with single pin fin and pin fin-dimple

Evaluation of the heat transfer and hydraulic performance of a new pin fin-dimple cooling system in a rectangular channel shows its advantage. The performance are compared with the pin fin system ones with 3-D Reynolds averaged Navier-Stokes (RANS) equations. The fluid flow and heat transfer analysis for the Reynolds numbers from 8000 to 70000 involved the shear stress transport turbulence model. The new system forms a high-intensity vortex around the pin fin-dimple that increases the near-wall turbulent mixing level that intensifies the heat transfer. The calculation results indicate increases of the averaged Nusselt number and the averaged friction factor of 7–13% and 7–12% respectively against the pin fin.

PENGARUH KOMPENSASI, DISIPLIN KERJA DAN MOTIVASI TERHADAP PRODUKTIVITAS KARYAWAN

The success of the company is determined by the human resources so that the company needs to meet the needs of employees so employees can work productively. Employee's punctuality is the ability of employees to complete their tasks effectively and efficiently. Employee productivity can be affected by several factors including compensation, work discipline and motivation. The purpose of this study is to determine the effect of compensation, work discipline and motivation to employee productivity. The research was conducted at Single Fin Restaurant &amp; Bar Bali. The number of respondents in this study was 79 people. In the data collection is done through the spread of questionnaires using Likert scale data measurement method. The analysis technique used in this research is multiple linear regression. The results of this study showed that each variable of compensation, work discipline and motivation partially have a positive and significant effect on employee productivity at Single Fin Restaurant &amp; Bar Bali.&#x0D; Keywords: compensation, work discipline, motivation, employee productiviy&#x0D;

On the Natural Convection Heat Transfer from an Inclined Surface with Porous Fins

This paper presents a simplified model to estimate the heat loss from an inclined porous-finned surface subjected to a constant heat flux under natural convection environment. The effect of attaching several infinitely long uniformly distributed porous fins at the hot surface is investigated and documented. A closed-form solution for the temperature at the base of a porous fin attached to an inclined surface is presented. The definitions of porous fin efficiency and effectiveness are introduced and estimated for several operating conditions and surface inclinations angles. It is found for a single fin that the temperature at the fin base and the fin efficiency is mainly controlled by a single parameter, $$ S_{\text{H}}^{*} = \frac{{D_{\text{a}} {\text{Ra}}^{*} \sin (\tau )}}{{K_{\text{r}}^{2} }} $$ . And when the value of SH* increases the surface temperature at the fin base and the fin efficiency decreases. Thus, for the same operating conditions, as the inclination angle increases the fin base temperature decreases, i.e., better heat transfer. Moreover, for a specific tilt angle, as the heat flux increases the fin efficiency decreases. Also, it is found that the fin effectiveness is mainly controlled by SH*, conductivity ratio, Kr and bare surface heat transfer coefficient. Moreover, an expression of the surface heat transfer effectiveness of a surface finned with multi fins is introduced.

Swimming performance of a bio-inspired robotic vessel with undulating fin propulsion

Undulatory fin propulsion exhibits a high degree of maneuver control—an ideal feature for underwater vessels exploring complex environments. In this work, we developed and tested a self-contained, free-swimming robot with a single undulating fin running along the length of the robot, which controls both forward motion and directional maneuvers. We successfully replicated several maneuvers including forward swimming, reversed motion, diving, station-keeping and vertical swimming. For each maneuver, a series of experiments was performed as a function of fin frequency, wavelength and traveling wave direction to measure swimming velocities, orientation angles and mean power consumption. In addition, 3D flow fields were measured during forward swimming and station-keeping using volumetric particle image velocimetry (PIV). The efficiency for forward swimming was compared using three metrics: cost of transport, wave efficiency and Strouhal number (St). The results indicate that the cost of transport exhibits a V-shape trend with the minimum value at low swimming velocity. The robot reaches optimal wave efficiency and locomotor performance at a range of 0.2–0.4 St. Volumetric PIV data reveal the shed of vortex tubes generated by the fin during forward swimming and station keeping. For forward swimming, a series of vortex tubes are shed off the fin edge with a lateral and downward direction with respect to the longitudinal axis of the fin. For station keeping, flow measurements suggest that the vortex tubes are shed at the mid-section of the fin while the posterior and anterior segment of the vortex stay attached to the fin. These results agree with the previous vortex structures based on simulations and 2D PIV. The development of this vessel with high maneuverability and station keeping performance has applications for oceanography, coastal exploration, defense, the oil industry and other marine industries where operations are unsafe or impractical for divers or human-piloted vessels.

Robust and local positional information within a fin ray directs fin length during zebrafish regeneration.

It has been proposed that cells are regulated to form specific morphologies and sizes according to positional information. However, the entity and nature of positional information have not been fully understood yet. The zebrafish caudal fin has a characteristic V-shape; dorsal and ventral fin rays are longer than the central ones. This fin shape regenerates irrespective of the sites or shape of fin amputation. It is thought that reformation of tissue occurs according to positional information. In this study, we developed a novel transplantation procedure for grafting a whole fin ray to an ectopic position and examined whether the information that specifies fin length exists within each fin ray. Intriguingly, when long and short fin rays were swapped, they regenerated to form longer or shorter fin rays than the adjacent host fin rays, respectively. Further, the abnormal fin ray lengths were maintained for a long time, more than 5months, and after further re-amputation. In contrast to intra-fin grafting, when fin ray grafting was performed between fish, cells in the grafts disappeared due to immune rejection, and the grafted fin rays adapted to the host position to form a normal fin. Together, our data suggest that the information that directs fin length does exist in cells within a single fin ray and that it has a robust property-it is stable for a long time and is hard to rewrite. Our study highlighted a novel positional information mechanism for directing regenerating fin length.