Flow Characterization of Bluff Bodies: A Two-Dimensional Transformation From Square to Triangular Cylinder

2021 ◽  
Author(s):  
Rajashree Borah ◽  
Siddhant Jain ◽  
Dyuman V. Joshi ◽  
Ujjwal K. Saha
Keyword(s):  
Drag Coefficient ◽  
Pressure Difference ◽  
Flow Behavior ◽  
Rear Surface ◽  
Body Height ◽  
Leading Edge ◽  
Stagnation Pressure ◽  
The Body ◽  
Two Dimensional ◽  
Recirculation Length

Abstract In the present study, two-dimensional unsteady, incompressible flow around a square body that is being transformed into a vertex oriented towards the flow configuration of a triangular body is numerically investigated at Re =100 using ANSYS FLUENT 19.0 software. The purpose is to explore the effect of this transformation on the wake characteristics of a square body with l/d = 1 to a triangular body with l/d = 0; where l is the length of lateral and front surface, and d is the body height. The effect on the flow behavior caused by the leading-edge transformation from the prospect of wake width, recirculation length and stagnation pressure difference is discussed. It is seen that as the l/d ratio decreases, the vortex strength increases which is attributed to the higher stagnation pressure difference value resulting in more intense rolling of the shedding vortex and a smaller wake width. For lower l/d, the fluid traverses a longer distance along the lateral surfaces resulting in greater loss of momentum and hence the lower vortex formation length. The mean drag coefficient is found to be minimum for l/d = 0.75 with stagnation pressure difference and recirculation length being the more dominating factor on this variation. The flow in all the cases separates at the rear surface and the general trend of decrease in drag coefficient with decrease in wake width is not followed. However, such modification leads to better aerodynamic outcome by weakening the periodic drag and lift forces.

Numerical Simulation and Control of the Flow Over a Backward Facing Ramp

2014 ◽  
Author(s):  
Charles-Henri Bruneau ◽  
Meriem Jedouaa ◽  
Khodor Khadra ◽  
Iraj Mortazavi
Keyword(s):  
Numerical Simulation ◽  
Recirculation Zone ◽  
Flow Behavior ◽  
Synthetic Jets ◽  
Direct Numerical Simulations ◽  
The Body ◽  
Two Dimensional ◽  
Rear Window ◽  
Simulation And Control ◽  
And Control

A two-dimensional backward facing ramp is used to represent a car simplified rear window. Direct numerical simulations are performed to describe the flow behavior over the ramp. Constant blowing jets and synthetic jets are applied on the body to control the flow. The results presented in this work show a significant reduction of the recirculation zone.

scholarly journals Prandtl–Batchelor flow past a flat plate with a forward-facing flap

1984 ◽  
Vol 143 ◽  
pp. 351-365 ◽  
Author(s):  
P. G. Saffman ◽  
S. Tanveer
Keyword(s):  
Flat Plate ◽  
Leading Edge ◽  
Vortex Sheet ◽  
Inviscid Flow ◽  
The Body ◽  
Two Dimensional ◽  
Rear Edge ◽  
Flow Past ◽  
Range Of Values ◽  
Streamline Method

Two-dimensional steady inviscid flow past an inclined flat plate with a forward-facing flap attached to the rear edge is considered for the case when a vortex sheet separates from the leading edge of the flat plate and reattaches at the leading edge of the flap, with uniform vorticity distributed between the vortex sheet and the body. Solutions are found for a particular geometry and a range of values of the vorticity. The method used to calculate the flow is an extension of a free-streamline method widely used in cases where the velocity is a constant on the separating streamline.

Flow past wing-body junctions

1984 ◽  
Vol 144 ◽  
pp. 191-215 ◽  
Author(s):  
F. T. Smith ◽  
J. Gajjar
Keyword(s):  
Body Surface ◽  
Three Dimensional ◽  
Leading Edge ◽  
The Body ◽  
Two Dimensional ◽  
Three Dimensional Flow ◽  
Flow Response ◽  
Flow Past ◽  
Short Wing ◽  
Corner Layer

The three-dimensional laminar flow past a junction formed by a thin wing protruding normally from a locally flat body surface is considered for wings of finite span but short or long chord. The Reynolds number is taken to be large. The leading-edge interaction for a long wing has the triple-deck form, with the pressure due to the wing thickness forcing a three-dimensional flow response on the body surface alone. The same interaction describes the flow past an entire short wing. Linearized solutions are presented and discussed for long and short two-dimensional wings and for certain three-dimensional wings of interest. The trailing-edge interaction for a long wing is different, however, in that the three-dimensional motions on the wing and on the body are coupled together and in general the coupling is nonlinear. Linearized properties are retrieved only for reduced chord lengths. The overall flow structure for a long wing is also discussed, including the traditional three-dimensional corner layer, which is shown to have an unusual singular starting form near the leading edge. Qualitative comparisons with experiments are made.

Flows over surface-mounted bluff bodies with different spanwise widths submerged in a deep turbulent boundary layer

2019 ◽  
Vol 877 ◽  
pp. 717-758 ◽  
Author(s):  
Xingjun Fang ◽  
Mark F. Tachie
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Separation Bubble ◽  
Body Height ◽  
Three Dimensional ◽  
The Body ◽  
Bluff Bodies ◽  
Two Dimensional ◽  
Wake Region ◽  
Separation Bubbles

The spatio-temporal dynamics of separation bubbles induced by surface-mounted bluff bodies with different spanwise widths and submerged in a thick turbulent boundary layer is experimentally investigated. The streamwise extent of the bluff bodies is fixed at 2.36 body heights and the spanwise aspect ratio ($AR$), defined as the ratio between the width and height, is increased from 1 to 20. The thickness of the upstream turbulent boundary layer is 4.8 body heights, and the dimensionless shear and turbulence intensity evaluated at the body height are 0.23 % and 15.8 %, respectively, while the Reynolds number based on the body height and upstream free-stream velocity is 12 300. For these upstream conditions and limited streamwise extent of the bluff bodies, two distinct and strongly interacting separation bubbles are formed over and behind the bluff bodies. A time-resolved particle image velocimetry is used to simultaneously measure the velocity field within these separation bubbles. Based on the dynamics of the mean separation bubbles over and behind the bluff bodies, the flow fields are categorized into three-dimensional, transitional and two-dimensional regimes. The results indicate that the low-frequency flapping motions of the separation bubble on top of the bluff body with $\mathit{AR}=1$ are primarily influenced by the vortex shedding motion, while those with larger aspect ratios are modulated by the large-scale streamwise elongated structures embedded in the oncoming turbulent boundary layer. For $\mathit{AR}=1$ and 20, the flapping motions in the wake region are strongly influenced by those on top of the bluff bodies but with a time delay that is dependent on the $AR$. Moreover, an expansion of the separation bubble on the top surface tends to lead to an expansion and contraction of separation bubbles in the wake of $\mathit{AR}=20$ and 1, respectively. As for the transitional case of $\mathit{AR}=8$, the separation bubbles over and behind the body are in phase over a wide range of time difference. The dynamics of the shear layer in the wake region of the transitional case is remarkably more complex than the limiting two-dimensional and three-dimensional configurations.

An Aerodynamic Study and Design Methodology for the 2009 Supermileage Body

2009 ◽  
Author(s):  
Joy Pathak ◽  
Andrzej Sobiesiak
Keyword(s):  
Drag Coefficient ◽  
Undergraduate Students ◽  
Three Dimensional ◽  
Leading Edge ◽  
Undergraduate Curriculum ◽  
Industrial Applications ◽  
The Body ◽  
Driver Model ◽  
Body Design ◽  
Low Mass

Computational Fluid Dynamics (CFD) has gained recognition as a valuable simulation tool for many industrial applications, creating immense opportunities for introducing CFD into standard undergraduate curriculum. This paper is focused on an extensive aerodynamic CFD study related to the 2009 Supermileage Vehicle. Supermileage Competition is a trademark competition conducted by the Society of Automotive Engineers (SAE). This paper provides an aid for future undergraduate students and young researchers interested in designing low drag vehicles. The major part of this study includes airfoil selections and three dimensional CFD iterations to optimize the body design. The methodology focuses on an inside-out approach to optimization of body shape through computation of aerodynamic forces on a low mass vehicle. The 2008 Supermileage car, after four design iterations, had a drag coefficient of 0.16. The 2009 body, in its final full body design, has a drag coefficient equal to 0.12, which is the lowest drag coefficient ever calculated for a University of Windsor Supermileage car. Due to the current economic state and reduced funding, an additional low budget vehicle was also designed and extensive aerodynamic studies were conducted to validate the design. The new low budget design includes a scoop at the leading edge of the vehicle and the CFD model included a driver model for accuracy. After several design iterations the low budget design yielded a drag coefficient of 0.14. Due to the weight savings, conforming to SAE rules, and considering the current economic conditions, the low budget design was finalized for the 2009 Supermileage Vehicle.

Mechanism of the Interaction of a Ramped Bleed Slot With the Primary Flow

2006 ◽  
Vol 129 (4) ◽  
pp. 669-678 ◽  
Author(s):  
B. A. Leishman ◽  
N. A. Cumpsty
Keyword(s):  
Static Pressure ◽  
Pressure Field ◽  
Computational Study ◽  
Flow Behavior ◽  
Rear Surface ◽  
Stagnation Pressure ◽  
Compressor Cascade ◽  
Primary Flow ◽  
Freestream Velocity ◽  
Blade Passage

An experimental and computational study of the ramped bleed slot in a compressor cascade is presented. The geometry is a circumferential slot downstream of the stator blade trailing edge, with endwall ramps inside the blade passage, and the paper builds on work previously reported for different bleed off-take geometries (Leishman et al., 2007, ASME J. Turbomach., 129, pp. 645–658; Leishman et al., 2007, ASME J. Turbomach., 129, pp. 659–668). The strong interaction between any bleed slot and the primary flow through the cascade can be strong, thereby causing the levels of loss and blockage in the primary flow leaving the blade passage to be increased at some bleed flow rates. Radial flow into the bleed slot is highly nonuniform because the blade-to-blade pressure field causes flow to enter the bleed slot preferentially where the static pressure is high, and to spill out into the primary flow where the static pressure is low. The mechanism for the ramped bleed slot is different from that described in the earlier papers for other geometries. For the ramped bleed slot a static pressure field, with large variations of static pressure in the circumferential direction, is set up in the slot because the endwall flow entering the slot has higher stagnation pressure downstream of the pressure surface than downstream of the suction surface of the upstream blades. The flow entering the slot with high stagnation pressure is brought to rest in a stagnation point on the downstream surface of the slot, and the consequent variation in static pressure on the rear surface sets tangential and radial components of velocity which are a large fraction of the freestream velocity. As well as demonstrating the mechanism for the flow behavior, the paper presents results of experiments and calculations to demonstrate the behavior and gives guidance for the design of bleed slots by stressing the fundamental features of the flow.

The use of Body Surface Index as a Better Clinical Health indicators Compare to Body Mass Index and Body Surface Area for Clinical Application

2018 ◽  
pp. 131-136
Author(s):  
Shirazu I. ◽  
Theophilus. A. Sackey ◽  
Elvis K. Tiburu ◽  
Mensah Y. B. ◽  
Forson A.
Keyword(s):  
Surface Area ◽  
Body Surface Area ◽  
Clinical Application ◽  
Body Surface ◽  
Body Height ◽  
Health Indicators ◽  
The Body ◽  
Body Parameters ◽  
The Relationship ◽  
Individual Body

The relationship between body height and body weight has been described by using various terms. Notable among them is the body mass index, body surface area, body shape index and body surface index. In clinical setting the first descriptive parameter is the BMI scale, which provides information about whether an individual body weight is proportionate to the body height. Since the development of BMI, two other body parameters have been developed in an attempt to determine the relationship between body height and weight. These are the body surface area (BSA) and body surface index (BSI). Generally, these body parameters are described as clinical health indicators that described how healthy an individual body response to the other internal organs. The aim of the study is to discuss the use of BSI as a better clinical health indicator for preclinical assessment of body-organ/tissue relationship. Hence organ health condition as against other body composition. In addition the study is `also to determine the best body parameter the best predict other parameters for clinical application. The model parameters are presented as; modeled height and weight; modelled BSI and BSA, BSI and BMI and modeled BSA and BMI. The models are presented as clinical application software for comfortable working process and designed as GUI and CAD for use in clinical application.

Physical fitness of people with moderate and considerable intellectual disabilities

Physiotherapy ◽  
2013 ◽  
Vol 21 (3) ◽  
Author(s):  
Marzena Ślężyńska ◽  
Grzegorz Mięsok ◽  
Kamila Mięsok
Keyword(s):  
Physical Activity ◽  
Intellectual Disability ◽  
Physical Fitness ◽  
Body Mass ◽  
Body Height ◽  
Abdominal Muscle ◽  
The Body ◽  
Intellectually Disabled ◽  
Fitness Tests ◽  
Abdominal Muscle Strength

AbstractIntroduction: The aim of the physical activity of the intellectually disabled is the strengthening of health, creating movement habits, promoting active recreation, and maintaining exercise capacity. Skillfully applied physical activity allows to mitigate the effects of pathology and create the compensations to enable the intellectually disabled people to live relatively independently. Physical activity and sport also increase their chances to integrate with their families, peers, and social environment.Materials and methods: The research targeted a group of 134 people with moderate or considerable intellectual disability (65 women and 69 men), aged 20-53 years, who participated in occupational therapy workshops in Jastrzębie Zdrój, Rybnik, and Żory. Physical fitness was assessed using the “Eurofit Special” test and balance tests. Measurements of body height and mass were also taken and then used to calculate the body mass index (BMI).Results: A salient somatic trait was the greater body mass relative to height among the persons with considerable disability, clearly illustrated by the BMI. This explained their greater heaviness in performing physical exercises. An even greater difference between participants with moderate and considerable intellectual disability was visible in physical fitness. Obviously, older persons did not achieve as good results in fitness tests as the younger ones, yet the participants were more differentiated by the level of disability than age. Most symptomatic differences to the disadvantage of the considerably disabled were observed in explosive strength, speed, abdominal muscle strength, and flexibility.Conclusions: Significant differences in fitness between the compared groups make it necessary to take into account the level of intellectual disability in the course of physical education and sport, at work, and in household duties.

scholarly journals Growth and development of children under 5 years of age with tetralogy of Fallot in a Chinese population

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xin Li ◽  
Jin Zhu ◽  
Jun An ◽  
Yuqing Wang ◽  
Yili Wu ◽  
...  
Keyword(s):  
Body Weight ◽  
Tetralogy Of Fallot ◽  
Growth Retardation ◽  
Growth And Development ◽  
Heart Defects ◽  
Body Height ◽  
Child Growth ◽  
The Body ◽  
Early Age ◽  
Local Conditions

AbstractCongenital Heart Defects (CHDs) are associated with different patterns of malnutrition and growth retardation, which may vary worldwide and need to be evaluated according to local conditions. Although tetralogy of Fallot (TOF) is one of the first described CHDs, the etiology outcomes in growth and development of TOF in early age child is still unclear in most cases. This study was designed to investigate the growth retardation status of Chinese pediatric TOF patients under 5 years old. The body height, body weight and body mass index (BMI) of 262 pediatric patients (138 boys and 124 girls) who underwent corrective surgery for TOF between 2014 and 2018 were measured using conventional methods. The average body height, body weight and BMI of the patients were significantly lower than WHO Child Growth Standards, while the most affected was body height. Meanwhile, higher stunting frequency and greater deterioration of both the body height and weight happened in elder age (aged 13–60 months) rather than in infant stage (aged 0–12 months) among these patients. Our results confirmed that intervention should be given at early age to prevent the growth retardation of TOF patients getting severer.

scholarly journals Detection of 15-bp Deletion Mutation within PLAG1 Gene and Its Effects on Growth Traits in Goats

Animals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 2064
Author(s):  
Zhenyu Wei ◽  
Ke Wang ◽  
Hui Wu ◽  
Zhen Wang ◽  
Chuanying Pan ◽  
...  
Keyword(s):  
Body Weight ◽  
Growth Traits ◽  
Body Height ◽  
The Body ◽  
Chest Circumference ◽  
Dairy Goat ◽  
Cashmere Goat ◽  
Indel Mutation ◽  
Body Stature ◽  
Body Index

Stature and weight are important growth and development traits for animals, which also significantly affect the productivity of livestock. Polymorphic adenoma gene 1 (PLAG1) is located in the growth-related quantitative trait nucleotides (QTN), and its variation has been determined to significantly affect the body stature of bovines. This study found that novel 15-bp InDel could significantly influence important growth traits in goats. The frequencies of genotypes of the 15-bp mutation and relationship with core growth traits such as body weight, body height, height at hip cross, chest circumference, hip width and body index were explored in 1581 individuals among 4 Chinese native goat breeds. The most frequent genotypes of Shaanbei white Cashmere goat (SWCG), Inner Mongolia White Cashmere goat (IMCG) and Guanzhong Dairy goat (GZDG) were II genotypes (insertion/insertion), and the frequency of ID genotype (insertion/deletion) was found to be slightly higher than that of II genotype in Hainan Black goat (HNBG), showing that the frequency of the I allele was higher than that of the D allele. In adult goats, there were significant differences between 15-bp variation and body weight, chest circumference and body height traits in SWCG (p < 0.05). Furthermore, the locus was also found to be significantly correlated with the body index of HNBG (p = 0.044) and hip width in GZDG (p = 0.002). In regard to lambs, there were significant differences in height at the hip cross of SWCG (p = 0.036) and hip width in IMWC (p = 0.005). The corresponding results suggest that the 15-bp InDel mutation of PLAG1 is associated with the regulation of important growth characteristics of both adult and lamb of goats, which may serve as efficient molecular markers for goat breeding.

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