Counterclockwise Vortex Research Articles

Robust design optimization of a turbine blade film cooling hole affected by roughness and blockage

High performance film cooling holes with complicated geometries have been regarded as impractical up to now because of manufacturability issues. However, recent advances in additive manufacturing (AM) technology have opened up new doors. Investigating characteristics of film holes built with AM, and finding the optimum shape considering these characteristics are now required to confirm their practical utility. In this paper, the performance of a high-efficiency film hole is numerically investigated. In-hole roughness and blade surface roughness are examined assuming an AM process, and contorted hole shape caused by partial blockage is also considered. A robust hole shape is obtained considering these uncertainties, utilizing a reference hole shape made by combining three cylindrical holes, which is meant to mitigate the detrimental effect of the counter-clockwise vortex pair. Main hole diameter, injection angle, and two angles for defining the two auxiliary holes are used as design variables to be optimized. For flow field and thermal analysis with roughness, compressible steady Reynolds averaged Navier-Stokes equations with a sand-grain roughness model are used. For the probabilistic assessment of each hole shape, Monte Carlo Simulations with the Kriging surrogate model is used, along with efficient global optimization (EGO) and a genetic algorithm. As a result, a high performance yet robust film cooling hole shape is obtained.

Left-handed molecules means left-spinning magnetic field created them

Since only left handed molecules are present in all living beings and the whole Universe left spinning magnetic field must have created the whole material world Since only anti vortices create such left spinning or counterclockwise spinning magnetic field anti vortices which spin leftward must have created the whole material world Indeed during solar activity the anti vortices are the ones that throw spinning energy balls create matter which are caught back by adjacent vortices which spin rightward or clockwise and suck energy and matter in Thus the presence of only left handed molecules in our Universe justifies that this material Universe was created by left spinning magnetic field which only anti vortices create

Transient three-dimensional flow structures of oblique jet impingement on a circular cylinder

A large eddy simulation (LES) was conducted to visualize the three-dimensional (3D) flow structures of a round jet impinging onto a circular cylinder with an inclination angle of 45°. The Reynolds number of the round jet is 11,800, and the distance from the nozzle exit to cylinder surface is four times the jet diameter. To verify the LES results, planar particle image velocimetry (PIV) measurements were obtained using the same flow conditions. After the impingement, the jet becomes a 3D curved wall jet and is attached to the cylinder wall far downstream due to the Coanda effect. The time-averaged pressure field indicates that the jet attachment is caused by the strong suction pressure after the impingement. However, the instantaneous pressure field reveals that positive and negative pressure bands repeatedly appear with 3D vortex structures near the impinging point. Ring-like rollup structures expand in the circumference direction over time, and weakened vortices are sustained longer in the limited spanwise boundary. The most notable feature is that a clockwise rotational vortex moves down to the wall when the counter-clockwise rotational vortex moves up from the surface, followed by a sign change of the instantaneous wall pressure. The ensemble-averaged velocity fields show good agreement between the LES and PIV results.

The Photospheric Vortex Flows during a Solar Flare

Abstract The rotational motions of the photospheric magnetic flux play a role in magnetic twist transportation between the corona and the solar interior. Using observations from the Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory (SDO), we found one counterclockwise and two clockwise vortex flows on the photosphere in the NOAA active region 12371 during the flare SOL2015-06-22T18:23 (M6.5). The counterclockwise vortex was located on the footpoint of the erupting hot channels observed by the Atmospheric Imaging Assembly (AIA) Telescope on board SDO. The two clockwise vortices resided on either side of the polarity inversion line. At these vortices, the impulsive and irreversible change in the photospheric vector magnetic field were detected. The resulting change in the photospheric Lorentz force provides a torque in each vortex, which has the same direction with each vortex. A magnetic field extrapolation model shows that the coronal field starting from the two clockwise vortices suffered significant shrinkage during the changeover period of the photospheric field. Moreover, some of the modeled field rooted in the counterclockwise vortex displays a pronounced expansion during the flare. These results suggest that the clockwise vortices could result from the contraction of the magnetic field lines during the flare, while the counterclockwise vortex may be attributed to the expansion of the eruptive flux rope as observed in the AIA images.

Active Flow Control of Dynamic Stall by Means of Continuous Jet Flow at Reynolds Number of 1 × 106

We have studied the influence of a tangential blowing jet in dynamic stall of a NACA0012 airfoil at Reynolds number of 1 × 106, for active flow control (AFC) purposes. The airfoil was oscillating between angles of attack (AOA) of 5 and 25 deg about its quarter-chord with a sinusoidal motion. We have utilized computational fluid dynamics to investigate the impact of jet location and jet velocity ratio on the aerodynamic coefficients. We have placed the jet location upstream of the counter-clockwise (CCW) vortex which was formed during the upstroke motion near the leading-edge; we have also considered several other locations nearby to perform sensitivity analysis. Our results showed that placing the jet slot within a very small range upstream of the CCW vortex had tremendous effects on both lift and drag, such that maximum drag was reduced by 80%. There was another unique observation: placing the jet at separation point led to an inverse behavior of drag hysteresis curve in upstroke and downstroke motions. Drag in downstroke motion was significantly lower than upstroke motion, whereas in uncontrolled case the converse was true. Lift was significantly enhanced during both upstroke and downstroke motions. By investigating the pressure coefficients, it was found that flow control had altered the distribution of pressure over the airfoil upper surface. It caused a reduction in pressure difference between upper and lower surfaces in the rear part, while substantially increased pressure difference in the front part of the airfoil.

The Effect of Inflow Cannula Length on the Intraventricular Flow Field: An In Vitro Flow Visualization Study Using the Evaheart Left Ventricular Assist Device.

Left ventricular assist device (LVAD) inflow cannula malposition is a significant risk for pump thrombosis. Thrombus development is influenced by altered flow dynamics, such as stasis or high shear that promote coagulation. The goal of this study was to measure the intraventricular flow field surrounding the apical inflow cannula of the Evaheart centrifugal LVAD, and assess flow stasis, vortex structures, and pulsatility for a range of cannula insertion depths and support conditions. Experimental studies were performed using a mock loop with a customized silicone left ventricle (LV) and the Evaheart LVAD. A transparent inflow cannula was positioned at 1, 2, or 3 cm insertion depth into the LV and the velocity field in the LV midplane was measured for 2 levels of LVAD support: 1800 and 2300 rpm. The LV velocity field exhibits a diastolic vortex ring whose size, path, and strength are affected by the flow conditions and cannula position. During diastole, the large clockwise midplane vortex grows, but its circulation and kinetic energy are reduced with cannula insertion depth. The counterclockwise vortex is smaller and exhibits more complex behavior, reflecting a flow split at 3 cm. Overall, the 1 cm cannula insertion depth produces the flow pattern that exhibits the least apical flow stasis and greatest pulsatility and should correlate to a lower risk of thrombus formation.

Effect of the angle of attack on the transient lift during the interaction of a vortex with a flat plate. Potential theory and experimental results

The dynamics of a two-dimensional vortex interacting with a flat plate at different angles of attack α is analysed using potential flow theory based on conformal mapping varying the nondimensional separation distance h∕c of the upstream incoming vortex to the plate (c is the chord length of the plate) and the vortex intensity Γl. Transient lift forces measured in a wind tunnel are also compared with the potential theory results for a given Γl and several values of h∕c and α. For the Reynolds number considered in the experiments (about 25 000) it is found that the potential theory predicts reasonably well the transient fluctuation in the lift force provided that the separation distance is not too close to the critical one h∗∕c at which the vortex trajectory given by the potential theory bifurcates. We find that the separation distance generating the highest induced lift is around this critical value h∗∕c, which, according to the potential theory, is displaced about −2.3(1−0.07|Γl|1∕2)α in relation to the zero angle of attack for the same Γl. Potential theory also predicts that the maximum peak of the lift fluctuation depends on α only through the relative separation |h−h∗|∕c, and that the maximum lift is substantially larger when a clockwise vortex passes below the plate than when it passes above the plate, for the same vortex intensity Γl and relative separation distance. The opposite happens for a counter-clockwise vortex. This asymmetry in the maximum lift fluctuation increases slightly with |Γl|, approaching a ratio of almost two for large |Γl|.

Thermal-solutal capillary-buoyancy flow of a low Prandtl number binary mixture with various capillary ratios in an annular pool

In order to understand the influence of the capillary ratio on the coupled thermal-solutal capillary-buoyancy flow in an annular pool subjected to simultaneous radial temperature and solute concentration gradients, a series of three-dimensional numerical simulations are carried out by using the finite volume method. The annular pool was filled with the silicon-germanium melt with an initial silicon mass fraction of 1.99%. The Prandtl number and the Lewis number of the silicon-germanium melt are 6.37×10−3 and 2197.8, respectively. Results indicate that the coupled thermal-solutal capillary-buoyancy flow is steady and axisymmetric when the thermal capillary Reynolds number is relatively small. With the decrease of the capillary ratio, the stable flow pattern experiences three stages, including the single counter-clockwise vortex, the combination of clockwise and counter-clockwise vortexes, and the single clockwise vortex. Besides the special case of the capillary ratio Rσ=−1, the critical thermal capillary Reynolds number for the incipience of the three-dimensional flow decreases with the decrease of the capillary ratio. Seven kinds of three-dimensional flow patterns are observed in the annular pool, which are the petal-like pattern, spoke pattern, rosebud-like pattern, hydrosolutal waves, ear-like pattern, target-like pattern and copper coin-like pattern. Actual flow pattern is strongly dependent on the capillary ratio, thermal capillary Reynolds number and the aspect ratio.

Tunable storage states' transition in slotted ferromagnetic nanorings

In magnetic random access memory, free layers are used to store data bits as “0” or “1.” For free layers with slotted nanoring structures, the magnetization configuration of counterclockwise vortex state can be defined as “0” state, while clockwise vortex state as “1” state. It is important to have a controllable and stable state transition process to make sure that “0” state can switch to “1” state and vice versa. Up to now, it has seldom been reported that the transition process is heavily affected by the static anisotropy field Hk-stat of free layers. A sufficient Hk-stat will substantially reduce the probability of successful state transition. To increase the accuracy of writing data, the free layers must be prepared with a low anisotropy field. In this paper, we present a rotational sputtering method, which can finish the desired isotropic film preparation, and thus realize a stable state transition.

Combined-hole film cooling with the application of double flow control devices

In the modern gas turbine, film cooling system was applied to the turbine blades to provide thermal protection from extreme turbine inlet temperatures. Recent literature discovers that adding the double flow control device (DFCD) and combining two cylindrical holes (combinedhole) are the ways to further enhance the film cooling performances. In the present simulation work, the influence of DFCD on the combined-hole film cooling was investigated at different blowing ratios. The comparison between two different computational domains of combined-hole film cooling with and without DFCD was further discussed in the present work. The results show that increase the blowing ratio, M rise the overall performance of combined-hole film cooling with and without DFCD. Based on the different computational domain, combined-hole with DFCD has better lateral spread at M = 0.5 and M = 0.75 in comparison with the combined-hole without DFCD. However, due to large counter clockwise vortex produced by the combined-hole with DFCD, unsymmetrical film cooling coverage was formed along the streamwise direction at M = 1.0 and M =1.5. As the conclusion, combined-hole film cooling with DFCD has better performance at M = 0.5 and M = 0.75 while combined-hole film cooling without DFCD has better performance at high blowing ratio of M = 1.0 and M = 1.5.

Skin-friction drag reduction in turbulent channel flow based on streamwise shear control

It is known that stretching and intensification of a hairpin vortex by mean shear play an important role to create a hairpin vortex packet, which generates the large Reynolds shear stress associated with skin-friction drag in wall-bounded turbulent flows. In order to suppress the mean shear at the wall for high efficient drag reduction (DR), in the present study, we explore an active flow control concept using streamwise shear control (SSC) at the wall. The longitudinal control surface is periodically spanwise-arranged with no-control surface while varying the structural spacing, and an amplitude parameter for imposing the strength of the actuating streamwise velocity at the wall is introduced to further enhance the skin-friction DR. Significant DR is observed with an increase in the two parameters with an accompanying reduction of the Reynolds stresses and vorticity fluctuations, although a further increase in the parameters amplifies the turbulence activity in the near-wall region. In order to study the direct relationship between turbulent vortical structures and DR under the SSC, temporal evolution with initial eddies extracted by conditional averages for Reynolds-stress-maximizing Q2 events are examined. It is shown that the generation of new vortices is dramatically inhibited with an increase in the parameters throughout the flow, causing fewer vortices to be generated under the control. However, when the structural spacing is sufficiently large, the generation of new vortex is not suppressed over the no-control surface in the near-wall region, resulting in an increase of the second- and fourth-quadrant Reynolds shear stresses. Although strong actuating velocity intensifies the near-wall turbulence, the increase in the turbulence activity is attributed to the generation of counter-clockwise near-wall vortices by the increased vortex transport.

Vortex generation and control in a microfluidic chamber with actuations

In this paper, we present a novel method for vortex generation and control in a resonator-shaped microfluidic chamber with actuations. By varying the actuation conditions, including the working transducers, frequency, and voltage, two regimes of vortices, clockwise vortex (CW vortex) and counter-clockwise vortex (CCW vortex), are generated in the chamber. We show that the direction of the vortex can be conveniently shifted from clockwise to counterclockwise by switching the working transducers without interrupting the flow, and the intensity of the vortex can be regulated by the actuation frequency and voltage. It is proposed that the vortex generation in the present case is due to the instability of the actuation-induced pulsatile flow through the sudden expansion part at the outlet of the chamber, while the vortex control is realized through the asymmetric flows in the chamber induced by the upper or lower transducers. The reported method of vortex generation and control can be applied in microfluidic operations for mixing enhancement of multiple reagents and distribution of microparticles and nanoparticles.

Asymmetric distributions in pressure/load fluctuation levels during blade-vortex interactions

The separation distance (h/c) between vortex and blade is a critical parameter in blade-vortex interaction, which strongly affects the magnitudes of induced pressure fluctuations (peak-to-peak values) and noise on helicopters. Parallel blade-vortex interaction (BVI) was studied in a subsonic wind tunnel to better understand the flow physics of BVIs with small h/c values and further improve the current BVI alleviation schemes. A vortex was generated by a sudden pitch motion applied to an airfoil through a pneumatic system. As the vortex interacted with a downstream target airfoil in a parallel manner, the vortex dynamics and induced loads were studied. The induced pressure/load fluctuations were obtained from the unsteady pressure data on the target airfoil, and the flow fields during the interaction were visualized using particle image velocimetry (PIV). Despite the fact that a symmetric airfoil was studied, the pressure data clearly displayed an asymmetric distribution in fluctuation levels above and below the chord line (h/c=0). Maximum pressure and load fluctuations occurred when the vortex passed on one side of the symmetric airfoil with small h/c, rather than in the head-on case (h/c=0). This side of the airfoil is defined as the strong fluctuation side, with the opposite side defined as the weak fluctuation side. PIV data revealed that this phenomenon was directly related to the asymmetry in velocity field induced by the vortex. The load fluctuation level also exhibited weak dependence on the decay in vortex strength due to both viscous- and inviscid-type interaction with the airfoil. However, the role of vortex decay became insignificant at higher Reynolds number due to lower decay rate. These findings cleared some confusion in previous studies and suggested that the magnitude of BVI fluctuations could be reduced by passing the airfoil below a clockwise vortex or above a counter-clockwise vortex.

Impacts of shape and height of building roof on airflow and pollutant dispersion inside an isolated street canyon

ABSTRACTTwo-dimensional numerical simulations were performed using the FLUENT code to investigate the impacts of the shape and height of building roofs on flow and pollutant dispersion inside an isolated street canyon. The numerical model was validated against wind tunnel measured data. Five different roof shapes (vaulted, trapezoidal, slanted, upward wedge-shaped, and downward wedge-shaped roofs) and three different roof heights ( = 1/6, 1/3, and 1/2, where is the roof height and H is the building height) were considered in the simulations. The numerical results revealed that the vortical flow structure and pollutant distribution within an isolated canyon depend significantly on the shape and height of building roofs. A large unique clockwise vortex is established in the canyon, and thus the pollutants accumulate in the leeward side of the canyon for the vaulted and downward wedge-shaped roofs at = 1/6, 1/3, and 1/2, the trapezoidal roof at = 1/6 and 1/3, and the slanted and upward wedge-shaped roofs at = 1/6, while an upper clockwise vortex and a lower counterclockwise vortex are generated, and consequently the pollutants pile up in the windward side of the canyon for the trapezoidal roof at = 1/2 and the slanted and upward wedge-shaped roofs at = 1/3 and 1/2. In the one-vortex flow regimes, the vortex center moves upwards and the vortex size expands vertically as the roof height increases for the vaulted, trapezoidal, and downward wedge-shaped roofs. In the two-vortex flow regimes, the size and rotational speed of both the upper clockwise and lower counterclockwise vortices increase with roof height for the slanted and upward wedge-shaped roofs. At each of the three roof heights examined, the lowest pollution level occurs in the canyon with the downward wedge-shaped roof, suggesting that the downward wedged-shaped roof is more beneficial for pollutant removal from the isolated canyon than the vaulted, trapezoidal, slanted, and upward wedge-shaped roofs. Due to the establishment of two-vortex flow structures, the trapezoidal roof at = 1/2, the slanted roof at = 1/3 and 1/2, and especially the upward wedge-shaped roof at = 1/3 and 1/2 are unfavorable for pollutant dispersion and dilution in the canyon compared to the vaulted and downward wedge-shaped roofs.

Electrophoretic motion of a liquid droplet and a bubble normal to an air–water interface

Electrophoretic motion of a charged liquid droplet or a bubble normal to an air-water interface is investigated theoretically, motivated by the rapid development of various practical applications involving micro/nano emulsions, as well as the fascinating potentials of using the air-water interface as a platform for the two-dimensional colloidal crystallization, for instance.The presence of an air-water interface reduces the droplet/bubble mobility in general when the double layer touches the interface. Special attention is given to the boundary effect upon the convection-induced polarization effect of the double layer pertinent to highly charged colloids, which tends to slow down the particle motion in general. As demonstrated by various contour plots of both electric and flow fields, the presence of an air-water interface affects the particle motion mainly due to the deformation/confinement of the double layer when it touches the interface. An axisymmetric counterclockwise vortex flow around the droplet/bubble is observed which pumps up the counterions originally in the wake to the front region. This significantly alleviates the motion-deterring polarization effect when the thickness of the double layer is comparable to the droplet/bubble radius. The release of this brake (polarization effect) refuels the electric driving force of the droplet/bubble hence affects its motion near the interface as observed.Convenient charts of correction factors of the boundary effect, expressed as a function of separation distance, are provided to facilitate the possible usage by interested researchers and engineers.

Integrated Effects of Street Layouts and Wall Heating on Vehicular Pollutant Dispersion and their Reentry Toward Downstream Canyons

ABSTRACTVehicle emission is becoming one of the major sources of gaseous pollutants and aerosol particles in urban air environments. Apart from pollutant source control, sustainable street design is another significant technique to reduce street air pollution. Under the validation by wind tunnel data, this paper conducts computational fluid dynamic (CFD) simulations by RNG k-e model to investigate the impacts of typical street layouts and wall heating on the dispersion of gaseous pollutants and particles (diameter d = 1 µm, 5 µm, 20 µm) in the target street canyons and their reentry toward downstream streets. The dispersion processes of gaseous pollutants and fine particles (d = 1 µm) are found similar. For uniform street layouts (aspect ratio H/W = 1) with small Froude number (Fr = 0.19–0.38), leeward-wall heating, ground heating and all-wall heating significantly enhance the primary clock-wise vortex and improve pollutant dispersion, but windward-wall heating does not. Taller upstream buildings (H1/W = 2–3) produce a clockwise vortex over the target canyon and a much weaker counter-clockwise vortex within it, seriously weakening the capacity of pollutant dispersion. For large particles (d = 20 µm), the major fraction deposits onto street ground because the gravity force dominates particle transportation. For particles of d = 5 µm, the dispersion dynamics are more complicated: In the isothermal case less particles of d = 5 µm suspend in the target canyon than d = 1 µm because the gravity force and particle deposition are more important, however, with all-wall heating more particles of d = 5 µm float in the target canyon because the upward thermal buoyancy force reduces particle deposition onto the ground. Finally for both gaseous pollutants and particles, their bulk concentrations in downstream streets decrease exponentially with increasing distance from the target canyon, whose decreasing rates are quantified. Although further investigations are still required to propose a practical framework, this paper is one of the first attempts to quantify the capacity of street particle dispersion for street design purpose.

EFFECT OF ROTATION RATES ON THE LAMINAR FLOW AND HEAT TRANSFER PAST A CIRCULAR CYLINDER

In this work, forced convection heat transfer past a rotating circular cylinder with a constant non-dimensional rotation rate α varying from 0 to 6 was investigated for Reynolds numbers of 20-200 and a Prandtl number of 0.7. The numerical calculations are carried out by using a finite-volume method based commercial computational fluid dynamics solver FLUENT. The successive changes in the flow pattern are studied as a function of the rotation rate. Suppression of vortex shedding occurs as the rotation rate increases (α > 2). A second kind of instability appears for higher rotation speed where a series of counter-clockwise vortices is shed in the upper shear layer. The rotation attenuates the secondary instability and increases the critical Reynolds number for the appearance of this instability. In addition, time-averaged (lift and drag coefficients and Nusselt number) results were obtained and compared with the literature data. A good agreement was obtained for both the local and averaged values.

Effects of Inclination Angle on Mixed Convection Heat Transfer of a Nanofluid in a Square Cavity

In this work, effects of inclination angle and nanoparticle concentration on mixed convection of a lid-driven cavity which is filled by Al2O3/water nanofluid have been investigated numerically. Two-dimensional elliptical governing equations have been solved using the finite volume technique to investigate the hydrodynamics and thermal behaviors. The Nu number, streamline, and temperature distribution of the nanofluid flow are presented for two Ri. At Ri = 1 and 100, maximum cooling was achieved at α = 315. In some inclination angle ranges, average Nusselt number of the left wall is higher than the right one and vice versa. When a counterclockwise vortex appears at the near heated wall region and connects to the right-side wall, the Nu of the right-side wall increases. Also, when a clockwise vortex appears at the near heated wall and connects to the left one, the Nusselt number of the left-side wall increases. Average Nusselt number of the bottom wall (heated wall) decreases with increasing nanoparticle concentration, while the Nusselt number of the left and right walls (cooled walls) increases. However, in the cavity, natural convection could act against force convection and weaken its effect.

Abstract 13873: Quantitative Characteristics of Left Ventricular Vortex Flow in the Short and Long Axis Views by High Frame Rate Echocardiographic Particle Image Velocimetry

Background: Vortex flow in the left ventricle (LV) has three-dimensional structure and plays an important role in avoiding excessive dissipation of energy. However, quantitative characteristics of long and short axis (LAX and SAX) vortex flow have not been elucidated. Echocardiographic particle image velocimetry (Echo-PIV) is an emerging technique to evaluate instantaneous vortical flow inside the LV. However, it has a limitation of underestimation of high velocities due to limited frame rate. Moreover, previous investigations have mainly focused on vortex from LAX view. Therefore, we used high frame rate Echo-PIV to quantitate vortex flow in SAX as well as in LAX views to understand characteristics of vortex three-dimensionally. Methods: Echocardiographic contrast images of the LV SAX and LAX were acquired from 8 open-chest healthy dogs. The acquisition frame rate was 135 frames per second and the contrast bubbles density was optimized for blood flow analysis. Echo-PIV analysis was performed off-line by using commercially available software and vorticity data were calculated in the region of interest (ROI) throughout the cardiac cycle. ROI was manually placed on the vortex. Vortex strength was defined as the averaged vorticity within the ROI. Results: In SAX, counterclockwise vortex was seen near the anterior wall, and in LAX clockwise vortex was seen in the anterior mid-ventricle. Both in SAX and LAX views, vortex strength showed significant phasic variations being largest in isovolumic contraction (vortex strength, SAX 9.2±2.3/s, p<0.001; LAX -12.0±2.4/s, p<0.001), and smallest in isovolumic relaxation (SAX -0.8±0.8/s, p<0.001; LAX -1.9±1.9/s, p<0.001). Conclusion: High frame rate Echo-PIV successfully demonstrated a complicated pattern of intracardiac vortex with phasic variation of its strength throughout a cardiac cycle in both SAX and LAX. This method may be a useful tool to assess physiological role of vortex in the flow dynamics.

Effects of System Rotation on Vortical Structure in Wall Turbulence

Direct numerical simulations (DNSs) of rotating turbulent Poiseuille flows are performed to study the effects of both cyclonic and anticyclonic system rotation on the kinematics of the quasi-streamwise vortices. By using the second invariant of the deformation tensor, a number of streamwise vortices are detected and averaged in the wall vicinity where the intense sweep motion, i.e., the inrush motion of high-speed fluid toward the wall, is related to the quasi-streamwise vortices. The effects of the system rotation on the angle of vortex axis are clearly observed as studied in longitudinal vortices of the homogeneous shear flow. Moreover, by calculating the probability of the emergence of the counterclockwise vortices (CCVs) around a clockwise vortex (CV), we find that with increase in the anticyclonic system rotation, the probability increases and decreases in the ejection and sweep sides of a CV, respectively. In contrast, cyclonic system rotation attenuates CCVs in both sides of a CV, though it increases at the top of the CV. This distribution of CCVs is found to affect sweep motion related to the quasi-streamwise vortices.