Pressure Drag Research Articles

Dimples for Skin-Friction Drag Reduction: Status and Perspectives

Dimples are small concavities imprinted on a flat surface, known to affect heat transfer and also flow separation and aerodynamic drag on bluff bodies when acting as a standard roughness. Recently, dimples have been proposed as a roughness pattern that is capable of reducing the turbulent drag of a flat plate by providing a reduction of skin friction that compensates the dimple-induced pressure drag and leads to a global benefit. The question whether dimples do actually work to reduce friction drag is still unsettled. In this paper, we provide a comprehensive review of the available information, touching upon the many parameters that characterize the problem. A number of reasons that contribute to explaining the contrasting literature information are discussed. We also provide guidelines for future studies by highlighting key methodological steps required for a meaningful comparison between a flat and dimpled surface in view of drag reduction.

Prediction of drag components on rough surfaces using effective models

Owing to the multiscale nature and the consequent high-computational cost associated with simulations of flows over rough surfaces, effective models are being developed as a practical means of dealing with such flows. Existing effective models focus primarily on accurately predicting interface velocities using the slip length. Moreover, they are concerned mainly with flat interfaces and do not directly address the drag computation. In this work, we formulate the Transpiration-Resistance model in polar coordinates and address the challenge of computing drag components on rough surfaces. Like the slip length, we introduce two constitutive parameters called shear and pressure correction factors that encompass information about how the total drag is partitioned into viscous and pressure components. Computation of these non-empirical parameters does not necessitate solving additional microscale problems; they can be obtained from the same microscale problem used for the slip-length calculation. We demonstrate the effectiveness of the proposed parameters for the Couette flow over rough surfaces. Moreover, using the flow over a rough cylinder as an example, we present the accuracy of predicting interface velocity and drag components by comparing the effective model results with those obtained from geometry-resolved simulations. Numerical simulations presented in this paper prove that we can accurately capture both viscous and pressure drag over rough surfaces for flat- and circular-interface problems using the proposed constitutive parameters.

Experimental Study of Hydrodynamic Pressures Acting on a Submerged Gate

Vortical flow formed by a submerged hydraulic jump may produce significant hydrodynamic lift and drag pressures on a gate beneath the hydraulic jump. In this study, an experimental setup equipped with multi-pressure sensors was used to measure fluctuating impact pressures on the submerged gate for different flow conditions characterized by the inlet Froude number and submergence factor (S). Time-averaged and instantaneous pressure coefficients are evaluated based on simultaneous measurements of wall pressures at multiple locations, including those at the lip and downstream face of the gate. In particular, instantaneous lift pressure coefficients are observed to be independent of the submergence ratio for S > 0.6. It is found that low Froude number flows produce high surface pressure fluctuations and the dominant frequency of pressure fluctuations shifts to higher frequency as the Froude number increases. Pressure measurements for the free hydraulic jump suggest that the power spectra of lift pressure fluctuations are devoid of any significant energy level, whereas the resulting power spectra of the submerged flow exhibits significant energy level in the frequency range of 14-19 Hz. The proposed measurement system can be used for the in situ identification of hydrodynamic pressures acting on the gates in irrigation canals.

Impact of Buoyancy and Stagnation-Point Flow of Water Conveying Ag-MgO Hybrid Nanoparticles in a Vertical Contracting/Expanding Riga Wedge

Riga surface can be utilized to reduce the pressure drag and the friction of the submarine by stopping the separation of the boundary layer as well as by moderating turbulence production. Therefore, the current symmetry of the work investigates the slip impacts on mixed convection flow containing water-based hybrid Ag-MgO nanoparticles over a vertical expanding/contracting Riga wedge. In this analysis, a flat surface, wedge, and stagnation point are also discussed. A Riga surface is an actuator that contains electromagnetic where a span-wise array associated with the permanent magnets and irregular electrodes accumulated on a smooth surface. A Lorentz force is incorporated parallel to the surface produced by this array which eases exponentially normal to the surface. Based on the considered flow symmetry, the physical scenario is initially modeled in the appearance of partial differential equations which are then rehabilitated into a system of ordinary differential equations by utilizing the pertinent similarity variables. A bvp4c solver is engaged to acquire the numerical solution. The flow symmetry and the influences of pertaining parameters involved in the problem are investigated and are enclosed in graphical form. The findings confirm that the velocity reduces, and temperature enhances due to nanoparticle volume fraction. A modified Hartmann number increases the velocity and diminishes the temperature. Moreover, the suction parameter enhances the velocity profiles and reduces the dimensionless temperature profiles. The heat transfer gradually increases by diminishing the contracting parameter and increasing the expanding parameter.

Direct numerical simulation of different finite cylinders rolling on a horizontal surface: The thickness effects on the aerodynamics

The flow around a cylinder rolling along a horizontal ground plane is investigated using direct numerical simulation for a Reynolds number based on the cylinder diameter, D, of ReD=3×104. Three cylinder thicknesses, T/D=0.040, 0.126, and 0.400, are considered. The time-averaged drag coefficients are found to be 0.87, 0.69, and 0.97 for the three cylinders, respectively. The non-monotonic variation in drag coefficient with thickness suggests a transition in the proportion of contributions of friction and pressure drag to the total drag which changes about 30% with thickness increase. Indeed, the ratio of friction drag to pressure drag varies from 0.333 to 0.085 and finally to 0.013 for the three cylinders. The pressure coefficient become more negative in the aft of the thicker cylinders, because the cylinder become more bluff body which suggests more pronounced pressure drag. Temporal fluctuations in the drag coefficient associated with vortex shedding events increase monotonically with thickness, though the root-mean-square of the drag coefficient follows the same trend as the mean drag coefficient. The lift coefficients are −0.057, 0.066, and 0.64 for the three respective cylinders. The negative value for the thinnest cylinder indicates down force. The transition from negative lift on the thin cylinder to positive lift on the thick cylinder is associated with elevated surface pressure just upstream of the ground contact point as thickness increases. As the flow is more detached from the cylinder sides, the friction lift is less significant with thickness increase. Furthermore, the pressure coefficient is negative spatially larger in the top of the thicker cylinders which the expansion offers a more significant upward pressure lift.

Geometrical deep learning for performance prediction of high-speed craft

Computational Fluid Dynamics (CFD) has become an indispensable tool in the field of engineering design evaluation and optimisation in the maritime industry. Accurate modelling of flow around a ship’s hull and superstructure requires high fidelity CFD simulations due to complex nonlinear phenomena. On the other hand, high fidelity CFD simulations are computationally expensive, memory demanding and time-consuming, thus limiting design space exploration when used in design optimisation. In order to overcome these challenges, we propose using geometrical deep learning-based surrogate modelling trained with CFD simulations for maritime applications combined with automatic hyperparameters tuning. Our proposed framework can predict both flow fields (e.g pressure field) on the surface of the geometry and any overall scalar parameters (e.g drag force) given a three-dimensional shape input. Furthermore, proposed deep learning model is extended to provide uncertainty quantification over its predictions (assuming CFD as ground truth). Finally, our proposed deep learning-based surrogate model is applied to predict pressure distribution and drag force for wind drag and calm water-resistance of high-speed craft. Despite the common drawback of deep learning-based algorithms to require large datasets for training, our proposed solution can maintain high prediction accuracy even when trained with a very small dataset which makes it highly suitable for use during design optimisations.

Large-eddy simulation of supercritical free-surface flow in an open-channel contraction

Large-eddy simulations (LES) of supercritical flow in a straight-wall, open-channel contraction of 6° and contraction ratio of 2:1 are performed. The LES code solves the filtered Navier-Stokes equations for two-phase flows (water-air) and employs the level-set method. The simulation was validated by replicating a previously reported experiment. Contours of the time-averaged velocities indicate that the flow loses energy and momentum in the contracting channel. Further, secondary currents in the contraction are redistributing momentum and are responsible for local up-and down-flows. The turbulent kinetic energy reaches very high values at the entrance of the contraction, mainly contributed by the streamwise normal stress. The flow contains coherent turbulence structures which are responsible for carrying low-momentum from the bed and the water surface towards the channel centre. Flow deceleration results in significant turbulence anisotropy in the contracted section. It is shown that mainly pressure drag contributes to the energy loss in the contraction.

Partial Pressure Field for Airfoil Wave Drag

Far-field drag prediction methods have proven to be effective at capturing drag sources in both computational fluid dynamics and wind-tunnel testing analyses. Near-field decomposition, on the other hand, has been neglected due to the failure to divide pressure drag directly into its contributions to both form and wave drag. The work presented in this paper is an extension of previous research conducted into partial pressure fields that allow such a near-field drag decomposition. In particular, the current paper proposes a new partial pressure field that captures wave drag sources in two-dimensional compressible viscous flow. Pressure decompositions are performed on the conventional NACA0012 and RAE2822 airfoils, and the results are compared to those obtained by classical far-field decomposition, with reference data from previous studies providing a means of verification. Finally, the slotted natural laminar-flow airfoil, the S207, is analyzed to test the applicability of the decomposition method on multielement airfoils that are considered for next-generation aircraft design. It is demonstrated that an adjusted compressible pressure field captures wave drag as a reliable near-field method that correlates closely with the traditional far-field methods, particularly for typical transonic cases.

On the Kármán momentum-integral approach and the Pohlhausen paradox: Extension to a cylinder in crossflow with a potential farfield motion

In this work, the Kármán–Pohlhausen (KP) momentum-integral approach based on optimized fourth-order (MX4) polynomial approximations of the velocity and temperature profiles is applied to a classical benchmark problem, namely, that of a cylinder in crossflow with a variable pressure gradient. This enables us to extract closed-form expressions for both hydrodynamic and thermal boundary-layer parameters and then compare the newly found solutions to their counterparts obtained using Pohlhausen's cubic (KP3) and quartic (KP4) polynomials. As usual, the farfield around the cylinder is modeled using potential flow theory and the momentum-integral analysis is paired with Walz's empirical expression for the momentum thickness, which is based on a wide collection of experiments. This procedure permits retrieving explicit relations for the pressure-sensitive KP3, KP4, and MX4 velocity profiles across the boundary layer; one also obtains accurate approximations for the pressure distribution around the cylinder as well as an improved prediction of the separation point, namely, to within 0.87% of the actual location. In this process, refined estimates are produced for several characteristic parameters whose distributions are found to be in favorable agreement with experimental measurements and numerical simulations. These include the disturbance, momentum, and displacement thicknesses as well as the skin friction, pressure, and total drag coefficients. Finally, the thermal analysis is undertaken using both isothermal and isoflux boundary conditions. For each of these cases, closed-form analytical solutions are obtained for the local Nusselt number distribution around the cylinder, and these distributions are found to exhibit noticeably reduced errors relative to their classical values.

Mountain Waves Produced by a Stratified Shear Flow with a Boundary Layer. Part III: Trapped Lee Waves and Horizontal Momentum Transport

Abstract The boundary layer theory for nonhydrostatic mountain waves presented in Part II is extended to include upward-propagating gravity waves and trapped lee waves. To do so, the background wind with constant shear used in Part II is smoothly curved and becomes constant above a “boundary layer” height d, which is much larger than the inner layer scale δ. As in Part II, the pressure drag stays well predicted by a gravity wave drag when the surface Richardson number J > 1 and by a form drag due to nonseparated sheltering when J < 1. As in Part II also, the sign of the Reynolds stress is predominantly positive in the near-neutral case (J < 1) and negative in the stable case (J > 1) but situations characterized by positive and negative Reynolds stress now combine when J ∼ 1. In the latter case, and even when dissipation produces positive stress in the lower part of the inner layer, a property we associated with nonseparated sheltering in Part II, negative stresses are quite systematically found aloft. These negative stresses are due to upward-propagating waves and trapped lee waves, the first being associated with negative vertical flux of pseudomomentum aloft the inner layer, the second to negative horizontal flux of pseudomomentum downstream the obstacle. These results suggest that the significance of mountain waves for the large-scale flow is more substantial than expected and when compared to the form drag due to nonseparated sheltering.

Studi Karakteristik Aliran Udara Kendaraan dengan Penambahan Spoiler Belakang Standard Dan Lebih Panjang

The use of rear spoilers on MPV vehicles is often used by the public to get an aerodynamic vehicle body design. The understanding of the function of using rear spoiler accessories in the community is still low, so it is necessary to study the characteristics of air flow in aerodynamics. This study aims to determine the flow characteristics of MPV type vehicles with standard and longer rear spoiler installation. This research was conducted in a Subsonic Open Circuit wind tunnel with test section dimensions (365 x 365 x 1250) mm. The flow characteristics were observed experimentally that passed through the model surface resembling the first generation Toyota Avanza MPV with a ratio of 1:20 with variations of the standard and longer rear spoiler installation. Measurement of the flow velocity profile behind the vehicle test model was carried out at an X/L ratio of 0.32 from the leading edge with a speed adjusted to the Reynolds number value of 1.96 x 105. The flow characteristic observed was the pressure distribution (Cp) on the center line of the top surface. and under the test vehicle model, the flow momentum deficit behind the test vehicle model, the lift pressure coefficient (CLP), and the drag pressure coefficient (CDP). The results of data collection show that the installation of a standard and longer rear spoiler relatively increases the Cp value, the flow momentum deficit behind the vehicle model, the lift pressure coefficient (CLP) value and decreases the drag pressure coefficient (CDP) value. The biggest increase was in the installation of a longer rear spoiler with an increase in the Cp value of 4.7%, an increase in the flow momentum deficit by 1.27%, an increase in the CLP value by 0.11% and a decrease in the CDP value by 0.06% compared to the vehicle model without using a rear spoiler.

The evolution of turbulent micro-vortices and their effect on convection heat transfer in porous media

New insight into the contribution of the microscale vortex evolution to convection heat transfer in porous media is presented in this paper. The objective is to determine how the microscale vortices influence convection heat transfer in turbulent flow inside porous media. The microscale temperature distribution is analysed using flow visualization in two dimensions using streamlines and in three dimensions using the Q-criterion. The pertinent observations are supplemented with a comparison of surface skin friction and heat transfer using: (i) surface skin-friction lines and (ii) the joint probability density function of the pressure and skin-friction coefficients, along with the Nusselt number. The microscale flow phenomena observed are corroborated with the features of the frequency spectra of the drag coefficient and macroscale Nusselt number. The large eddy simulation technique is used in this study to investigate the flow field inside a periodic porous medium. The Reynolds numbers of the flow are 300 and 500. The porous medium consists of solid obstacles in the shape of square and circular cylinders. Two distinct flow regimes are represented by using the porosities of 0.50 and 0.87. The results show that the surface Nusselt number distribution is dependent on whether the micro-vortices are attached to or detached from the surface of the obstacle. The spectra of the macroscale Nusselt number and the pressure drag are similar, signifying a correlation between the dynamics of heat transfer and the microscale turbulent structures. Both vortex shedding and secondary flow instabilities are observed that significantly influence the Nusselt number. The fundamental insight gained in this paper can inform the development of more robust macroscale models of convection heat transfer in turbulent flow in porous media.

Multi-Parametric Investigations on Aerodynamic Force, Aeroacoustic, and Engine Energy Utilizations Based Development of Intercity Bus Associates with Various Drag Reduction Techniques through Advanced Engineering Approaches

The impacts of conflicting aerodynamic forces and side drifting forces are the primary unstable elements in automobiles. The action of an unstable environment in automobile vehicles increases the chance of an accident occurring. As a result, much study is required to determine how opposing aerodynamic forces and side drifting force affects function, as well as how to deal with them for safe and smooth navigation. In this work, an intercity bus is chosen as a main object, and computational fluid dynamics (CFD) analysis is used to estimate aerodynamic forces on the bus in all major directions. Experimentation is also carried out for validation reasons. CFD findings for a scaled base model and a dimple-loaded model based on experimental results from a subsonic wind tunnel are demonstrated to be correct. The drag forces generated by CFD simulations on test models are carefully compared to the experimental drag findings of same-dimensioned models. The error percentages between the results of these two methods are acquired and the percentages are determined to be within an acceptable range of significant limitations. Following these validations, CATIA is used to create a total of nine distinct models, the first of which is a standard intercity bus, whereas the other eight models are fitted with drag reduction techniques such as dimples, riblets, and fins on the surface of their upper cumulus side. A sophisticated computational tool, ANSYS Fluent 17.2, is used to estimate the comparative assessments of the predictions of aerodynamic force fluctuations on bus models. Finally, dimples on the top and side surfaces of the bus model (DESIGN–I) are proposed as a more efficient model than other models because dimples are a vital component that may lower pressure drag on the bus by 18% in the main flow direction and up to 43% in the sideslip direction. Furthermore, by minimizing the different aerodynamic force sources without impacting the preparatory needs, the proposed model may provide comfortable travel. The real-time bus is created, and the finalized drag reduction is applied to the optimized places over the whole bus model. In addition, five distinct size-based bus models are developed and studied in terms of aerodynamic forces, necessary energy to resist aerodynamic drag, required forward force for successful movement, instantaneous demand for particular power, and fuel consumption rate. Finally, the formation of aeroacoustic noise owing to turbulence is estimated using sophisticated computer simulation. Last, for real-time applications, multi-parametric studies based on appropriate intercity buses are established.

Relationship between the base pressure and the velocity in the near-wake of an Ahmed body

We investigate the joint dynamics of the near-wake velocity and the base pressure of a square back Ahmed body. We identify two modes that are responsible for most of the pressure drag variations. We show that the turbulent large-scale velocity field in the wake can be recovered from base pressure measurements.

Steady flow past elliptic cylinders with blockage effects

In the present work, steady two-dimensional flow past elliptic cylinders with different aspect ratios (Ar) have been investigated for Reynolds number (Re) up to 200. Main characteristics such as the bubble length, bubble width, separation Reynolds number, separation angle, drag coefficient, coefficients of the front and rear stagnation pressure, and the maximum vorticity on the cylinder surface have been obtained. Least squares fit equations for some of these quantities have also been presented. In the special case of a circular cylinder, results computed with the largest domain show that the bubble length, bubble width, maximum vorticity on the cylinder surface, coefficient of pressure drag, coefficient of total drag, and flow separation angle are linear functions of Re, Re0.5, Re0.35, Re−0.4, Re−0.5, and Re−0.1, respectively. As Ar changes, the trends in the growth, with respect to Ren (with the corresponding index), for the bubble length, bubble width, and the maximum surface vorticity deviate from their linear nature. The effect of blockage on the steady flow characteristics has been studied by changing the location of the side boundaries. In certain cases, the flow properties are found to vary in a non-monotonic fashion with the change in the blockage. An explanation based on the dual role of the side boundaries in promoting and suppressing the growth of the corresponding flow property is offered.

Vortex shedding, flow separation, and drag coefficient in the flow past an ellipsoid of different aspect ratios at moderate Reynolds number

Incompressible viscous flow past an ellipsoid of different aspect ratios (ARs, the ratio of the vertical to the horizontal axis of the ellipsoid, is ranged from 0.5 to 2) at a Reynolds number of 300 is investigated numerically by a finite volume method with adaptive mesh refinement, and the effects of different aspect ratios on vortex shedding, flow separation, and drag coefficient are analyzed in detail. The accuracy of the present results is ascertained by comparing the present drag coefficient and Strouhal number with other literature studies. The results show that the Strouhal frequency of vortex shedding decreases and the magnitude of vortex shedding becomes weaker with an increase in the aspect ratio. In particular, a secondary frequency will occur within a certain interval of 0.8 ≤ AR ≤ 1.2. The vortex shedding appears as a hairpin vortex at AR ∈ [0.5, 1.6], whereas it becomes a double-line vortex at AR ≥ 1.8. Both the upper flow separation angle and the length of the separation bubble increase with an increase in the aspect ratio. The flow separation is symmetrical about the (x, z)-plane only at 0.5 ≤ AR ≤ 0.7 and AR ≥ 1.8. Furthermore, the total drag coefficient and the pressure drag coefficient both increase gradually with an increase in the aspect ratio. Due to the trend of the contact area between the fluid and the surface of the ellipsoid, the friction drag coefficient decreases first (AR ≤ 1) and then increases (AR ≥1). The pressure drag coefficient reinforces the contribution to the total drag coefficient, and the contribution of the pressure drag coefficient grows with an increase in the aspect ratio.

Cruise Drag Reduction Through Chord Modulation with Application to Distributed Propulsion

An investigation into the effect of airfoil chord reduction on the drag of a fixed-span wing is presented. Chord reduction is characterized within two scenarios: fixed lift and lift coefficient yielding an increasing flight velocity, and fixed lift and flight velocity necessitating a variable lift coefficient. The dependence on chord of the airfoil’s zero lift and sectional pressure drag was established though examination of experimental data for the selected airfoil, a NACA 0012. Analytic expressions are subsequently derived that quantify the behavior of the profile and wing vortex drag. The test case is an aircraft geometry based on a Cessna 210. The analysis shows that for the variable velocity case, both zero lift and sectional pressure drag increase with chord reduction (which requires increased flight velocity), whereas vortex drag reduces significantly. The net result is a reduction in wing drag. For the fixed flight velocity case, chord reduction increases both the sectional pressure drag and the wing’s vortex drag, however, the zero lift drag drops markedly, yielding a net drag benefit. Including the drag contribution of the fuselage and empennage shows that a chord reduction necessitating a higher flight velocity always causes an overall drag increase. For the fixed flight velocity case, a chord reduction still yields a drag reduction, but of lesser magnitude than for the wing alone.

Rational Analysis of Drag Reduction Variation Induced by Surface Microstructures Inspired by the Middle Section of Barchan Dunes at High Flow Velocity

Aerodynamic drag reduction is a key element for the design of aircrafts, and it is also considered to be affected by the flow velocity. Herein, the influence of high flow velocity on the drag reduction induced by the surface microstructure inspired by a cross-section of barchan dune was investigated by the computational fluid dynamics method in this work. Overall, the drag reduction ratio was decreased while the pressure drag and viscous resistance enhanced simultaneously with the augmentation of flow velocity. Otherwise, drag analysis revealed that the total drag was a power function of flow velocity, which meant that the effect of flow velocity on drag was extremely fierce. Additionally, the microstructure improved the thickness of the boundary layer with a growth rate of 14.2%, and then reduced the viscosity resistance with limits during the development process of flow velocity. Furthermore, the micro-vortex caused by the surface microstructure provided the reverse wall shear stress, with the maximum value ranging from −4.77 Pa to −51.27 Pa, and then reduced the velocity gradient above the microstructure, thereby improving the drag reduction. However, both Reynolds-averaged Navier-Stokes (RANS) and large eddy simulation (LES) calculations showed that the excessive velocity could lead to the dissipation of micro-vortex, which augmented the contact area between the fluid and the surface, resulting in the enlargement of viscous resistance. Finally, it was confirmed that the variation of surface microstructure height had a significant influence on drag reduction at high flow velocity. The underlying mechanism of drag reduction could also provide theoretical guidance for the design and optimization of drag reduction coatings in aeronautical applications.

Thermal-hydraulic performance enhancement of solar receiver channel by flapped V-baffles

Thermal-hydraulic performance investigation in a solar receiver channel equipped with a vortex flow generator, namely, flapped V-shaped baffle (FVB) on the absorber has been experimentally carried out. The purpose of using the square flaps on the V-baffle was to decline the pressure drag by directing the impact air to the absorber surface. The working fluid was air flowing into the uniform heat-fluxed channel at Reynolds number (Re) between 5300 and 23,600. The FVBs with 45°attack angle (α) were placed periodically on the absorber with the upstream V-apex arrangement. The FVB characteristics included three relative baffle-pitches (RP) and four flap angles (β)at one relative baffle height (RB=0.5) and flap length (b1/b = 0.4) were examined to obtain the optimum RP and β values. The present investigation has revealed that the FVB gives a considerable decrease in friction loss when compared with the solid V-baffle (β = 0) while the heat transfer rate reduces a little. The FVB with β = 45°, RP = 1.5 yields the greatest thermal performance around 2.5 as a result of the injecting air flows from the flap opening aside from the reduced friction loss. For the current experimental data, the Nusselt number and friction factor correlations were determined in the form of a function of the geometric FVB parameters and Re.

Drag and Lift Characteristics of Different Handlebars and Front-Fairing Combinations Used in Two-Wheelers: A CFD Approach

Two-wheelers with a total industrial volume of 50 million units over the past decade are one of the most popular modes of transport. Two-wheelers irrespective of the fueled engine or electric variant, are steered by means of the Handle-bar. The handlebar type and quality affects the operational characteristics of the two-wheeler as well as the physical fatigue of the rider. Handle-bar designs affect the parameters like ergonomics, maneuverability, rider comfort, and aerodynamics. The target of this study was to analyze the aerodynamic response of different handlebar types with and without the front fairings. To simulate the flow and optimize the streamline, Ansys-CFX® tool was used. In the study, focus was given to the frontal area of the two-wheeler without the rider. The key metrics considered for the aerodynamic analysis included the pressure distribution, velocity distribution, drag and lift coefficients. From the aerodynamic studies, the drag handlebar was found to offer the minimum drag while the clip-on handlebar offered the lowest lift.