Increase In Drag Research Articles

Drag reduction of a square-back bluff body under constant cross-wind conditions using asymmetric shear layer forcing

Highly resolved computations using Delayed Detached Eddy Simulations (DDES) of a canonical Windsor body are carried out. The flow around the car model, which is investigated imposing different yaw angles (up to 10°), is perturbed via a small square cylinder. This control element, whose length covers the whole height of the car model, is positioned at different streamwise locations on the windward face of the model. Depending on the location of the cylinder and the initial yaw angle of the model, drag increase or decrease up to 8% are observed. This sensitivity of the drag to the streamwise location of the cylinder is connected with the relative position of the flow reattachment on the side of the model after separation, which is caused by the cylinder. In the drag-optimal case where the flow reattachment occurs just at the streamwise location of the base, the asymmetry of the wake is reduced and the pressure in the wake is globally recovered. The flow mechanisms by which the drag reduction occur are twofold: (i) the flow is deviated inwards by the in-wash induced by the flow reattachment at the trailing-edge, thus acting as an inward-oriented flap, and (ii) the windward shear layer is forced by the turbulent field developing along the separated region of the perturbing cylinder.

Direct numerical simulation of supersonic turbulent flows over rough surfaces

We perform direct numerical simulation of supersonic turbulent channel flow over cubical roughness elements, spanning bulk Mach numbers $M_b=0.3$ – $4$ , both in the transitional and fully rough regime. We propose a novel definition of roughness Reynolds number which is able to account for the viscosity variations at the roughness crest and should be used to compare rough-wall flows across different Mach numbers. As in the incompressible flow regime, the mean velocity profile shows a downward shift with respect to the baseline smooth wall cases, however, the magnitude of this velocity deficit is largely affected by the Mach number. Compressibility transformations are able to account for this effect, and data show a very good agreement with the incompressible fully rough asymptote, when the relevant roughness Reynolds number is used. Velocity statistics present outer layer similarity with the equivalent smooth wall cases, however, this does not hold for the thermal field, which is substantially affected by the roughness, even in the channel core. We show that this is a direct consequence of the quadratic temperature–velocity relation which is also valid for rough walls. Analysis of the heat transfer shows that the relative drag increase is always larger than the relative heat transfer enhancement, however, increasing the Mach number brings data closer to the Reynolds analogy line due to the rising relevance of the aerodynamic heating.

Near-wall turbulence alteration with the transpiration-resistance model

A set of boundary conditions called the transpiration-resistance model (TRM) is investigated in altering near-wall turbulence. The TRM was proposed by Lacis et al. (J. Fluid Mech., vol. 884, 2020, p. A21) as a means of representing the net effect of surface micro-textures on their overlying bulk flows. It encompasses conventional Navier-slip boundary conditions relating the streamwise and spanwise velocities to their respective shears through the slip lengths $\ell _x$ and $\ell _z$ . In addition, it features a transpiration condition accounting for the changes induced in the wall-normal velocity by expressing it in terms of variations of the wall-parallel velocity shears through the transpiration lengths $m_x$ and $m_z$ . Greater levels of drag increase occur when more transpiration takes place at the boundary plane, with turbulent transpiration being predominately coupled to the spanwise shear component for canonical near-wall turbulence. The TRM reproduces the effect of a homogeneous and structured roughness up to $k^{+}\approx 18$ , encompassing the regime of smooth-wall-like turbulence described using virtual origins (Luchini, 1996 Reducing the turbulent skin friction. In Computational Methods in Applied Sciences’ 96 (Paris, 9–13 Sept. 1996), pp. 465–470. Wiley; Ibrahim et al., J. Fluid Mech., vol. 915, 2021, p. A56) and slightly beyond it. The transpiration factor is defined as the product of the slip and transpiration lengths, i.e. $(m\ell )_{x,z}$ . This factor contains the compound effect of the wall-parallel velocity occurring at the boundary plane and increased permeability, both of which lead to the transport of momentum in the wall-normal direction. A linear relation between the transpiration factor and the roughness function is observed for regularly textured surfaces in the transitionally rough regime of turbulence. This shows that such effective flow quantities can be suitable measures for characterizing rough surfaces in this flow regime.

Selection Criteria for Biplane Wing Geometries by Means of 2D Wind Tunnel Tests

This paper presents a study based on wind tunnel research on biplane configurations. The objective of this research is to establish an experimental basis for relationships between the main geometrical parameters that define a biplane configuration (stagger, decalage, gap, and sweep angle) and the aerodynamic characteristics (CL, CD). This experimental study focuses on a 2D approach. This method is the first step towards dealing with the issue, and it allows the variables involved in the tests to be reduced. The biplane configuration has been compared with the monoplane configuration to analyze the viability for implementing the biplane configuration in the field of application for micro air vehicles (MAV). At present, the biplane and other unusual configurations have not been a common design for MAV; however, they do have unlimited future potential. A set of experimental tests were carried out on various biplane configurations at low Reynolds numbers, which allowed the criteria for selecting the best wing configuration to be defined. The results obtained here show that the biplane configuration provides a higher maximum lift coefficient (CLmax) than the planar wing (monoplane). Furthermore, it has a larger wetted surface than the planar configuration, so the parasitic drag increases for the biplane configuration. This research is focused on a drone flight regime (low Reynolds number), and in this case, the parasitic drag (profile drag) has an important role in the total drag of the airplane. This study considers whether the reduction in the induced drag due to three–dimensional configuration (biplanes, box–wings, and joined–wings) can reduce the total drag or if the increase in the parasitic drag is bigger. Additionally, the increase in lift and the decrease in parasitic drag (profile drag) will be studied to determine if they have a greater influence on the performance of the airplane than the increase in structural weight. Further research is planned to be performed on 3D prototypes, with the selected configurations, and applied to nonconventional wing planforms.

Drag reduction in wall-bounded turbulence by synthetic jet sheets

A turbulent drag-reduction method employing synthetic jet sheets in a turbulent channel flow is investigated by direct numerical simulations. The jet sheets are wall-parallel and produced by periodic blowing and suction from pairs of thin slots aligned with the main streamwise flow. By varying the slot height and the jet-sheet angle with respect to the spanwise direction, drag-reduction margins between $10\,\%$ and $30\,\%$ are obtained for jet-sheet angles between $45 ^{\circ }$ and $75 ^{\circ }$ , while a drag increase of almost 100 % is computed when the jet sheets are spanwise-oriented. When global skin-friction drag reduction occurs, the wall-shear stress near the jet-sheet exits increases during suction and decreases during blowing, while the velocity fluctuations weaken during suction and intensify during blowing. The global drag-reduction effect is produced by a finite counter flow induced by the nonlinear interaction between the jet-sheet flow and the main flow, although the turbulent intensity and Reynolds shear stresses increase. The power spent to generate the jet sheets is computed by modelling numerically the actuator underneath the channel flow as a piston oscillating sinusoidally along the spanwise direction in a round-shaped cavity from which the fluid is released into the channel through the cavity exits. A power balance leads to the computation of the efficiency of the actuator system, quantifying the portion of the piston power that is lost as internal power fluxes and heat transfer through the cavity walls. For the tested configurations, the power consumed by the piston to generate the jet sheets is larger than the power saved thanks to the drag reduction.

Broadband trailing edge noise reduction through porous velvet-coated serrations

This study experimentally investigates the potential of using combinations of trailing edge serrations and thin porous membrane/velvet structures for turbulent boundary layer trailing edge noise reduction. The experiments were conducted in an anechoic wind tunnel, with a flat plate model as the baseline model. The chord-based Reynolds number ranged between 2×105 and 5×105, and the boundary layers were fully tripped near the leading edge. Two different installation methods were tested, where the serration structure was aligned/misaligned with the undisturbed wake flow. It was observed that the noise reduction capability of the conventional serrations deteriorates significantly when the serrations are misaligned with the flow, while the performances of the combined structures are only slightly affected by flow misalignment. A novel combined treatment is developed, in which the trailing edge serrations are surrounded by serrated porous velvet structures. This treatment is found to outperform the unmodified serrations and can achieve approximately 10 dB noise reduction in both flow-aligned and flow-misaligned conditions, within a wide frequency range corresponding to a boundary layer thickness-based Strouhal number Stδ between 0.3 to 1. A 30%–40% increase in the aerodynamic drag due to the velvet structures was observed. Further hotwire wake survey revealed the possible mechanisms for the additional noise reduction capability of the combined treatments.

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.

Fluid-Structure Interaction Analysis of a Competitive Car during Brake-in-Turn Manoeuvre

The relationship between the presented work and energy conservation is direct and indirect. Most of the literature related to energy-saving focuses on reducing the aerodynamic drag of cars, which typically leads to the appearance of vehicle motion instabilities at high speeds. Typically, this instability is compensated for by moving aerodynamic body components activated above a certain speed and left in that position until the vehicle speed drops. This change in vehicle configuration results in a significant increase in drag at high velocities. The presented study shows a fully coupled approach to fluid–structure interaction analyses of a car during a high-speed braking-in-turn manoeuvre. The results show how the aerodynamic configuration of a vehicle affects its dynamic behaviour. In this work, we used a novel approach, combining Computational Fluid Dynamics (CFD) analysis with the Multibody Dynamic System. The utilisation of an overset technique allows for car movement in the computational domain. Adding Moving Reference Frame (MRF) to this motion removes all restrictions regarding car trajectory and allows for velocity changes over time. We performed a comparative analysis for two aerodynamic configurations. In the first one, a stationary rear airfoil was in a base position parallel to a trunk generating low drag. No action of the driver was assumed. In the second scenario, brake activation initiates the rotation of the rear airfoil reaching in 0.1 s final position corresponding to maximum aerodynamic downforce generation. Also, no action of the driver was assumed. In the second scenario, the airfoil was moving from the base position up to the point when the whole system approached its maximum downforce. To determine this position, we ran a separated quasi-steady analysis in which the airfoil was rotating slowly to avoid transient effects. The obtained results show the importance of the downforce and load balance on car stability during break-in-turn manoeuvres. They also confirm that the proposed methodology of combining two independent solvers to analyse fluid–structure phenomena is efficient and robust. We captured the aerodynamic details caused by the car’s unsteady movement.

Kinetic modeling of fractal aggregate mobility

Although the mobility or transport parameters, such as lift drag and pitching moments for regular-shaped particulates, are widely studied, the mobility of irregular fractal-like aggregates generated by the aggregation of monomers is not well understood. These particulates which are ubiquitous in nature, and industries have very different transport mechanisms as compared to their spherical counterpart. A high-fidelity direct simulation Monte Carlo (DSMC) study of two fractal aggregates of different shapes or dimensions is undertaken in the slip and transitional gas regime to understand the underlying mechanism of gas-particle momentum transfer that manifests as the orientation-averaged mobility parameters of the particulates. The study specifically focuses on the viscous contribution of these parameters and develops a non-linear correlation for drag and lift parameters p and q obtained from DSMC by normalizing the axial and lateral forces. The drag parameter p predicted a monotonic increase in fractal particulate drag with respect to a spherical monomer while the lift parameter q shows an initial increasing trend but a decreasing tendency toward the high Mach number or high compressibility regime. The approximate model that captures the compressibility and rarefaction effects of the fractal mobility is used to study the evolution of these particulates in a canonical Rankine vortex to illustrate the wide disparity in the trajectories of the fractal aggregate vs a spherical geometry approximation generally found in the literature.

Keels of boxfish carapaces strongly improve stabilization against roll.

Boxfish (Ostraciidae) have peculiar body shapes, with conspicuous keels formed by their bony carapaces. Previous studies have proposed various hydrodynamic roles for these keels, including reducing drag during swimming, contributing to passive stabilization of the swimming course, or providing resistance against roll rotations. Here, we tested these hypotheses using computational fluid dynamics simulations of five species of Ostraciidae with a range of carapace shapes. The hydrodynamic performance of the original carapace surface models, obtained from laser scanning of museum specimens, was compared with models where the keels had been digitally reduced. The original carapaces showed no reduced drag or increased passive stability against pitch and yaw compared to the reduced-keel carapaces. However, consistently for all studied species, a strong increase in roll drag and roll-added mass was observed for the original carapaces compared to the reduced-keel carapaces, despite the relatively small differences in keel height. In particular, the damping of roll movement by resistive drag torques increased considerably by the presence of keels. Our results suggest that the shape of the boxfish carapace is important in enabling the observed roll-free forward swimming of boxfish and may facilitate the control of manoeuvres.

Identification of wake vortices in a simplified car model during significant aerodynamic drag increase under crosswind conditions

Identification of wake vortices in a simplified car model during significant aerodynamic drag increase under crosswind conditions

An Investigation of Aerodynamic Characteristics of Two Bluff Bodies in Close Longitudinal Proximity – Sensitivity to Front-End Geometry

<div class="section abstract"><div class="htmlview paragraph">With an increasing focus on the reduction of greenhouse gases by the transport industries and continued development of connected and autonomous vehicle systems, the potential for aerodynamic drag reduction by means of managed systems of vehicles travelling in close-proximity, termed “platooning”, has continued as topic for research. Early-work in passenger-car platooning was conducted by varying the spacing between vehicles in homogeneous platoons. More recently the use of systematic changes in upper-body geometry has provided data for another variable in the assessment of platooning characteristics. The results of the investigation described in this paper adds to previously published platooning results using the Windsor reference model. For this investigation a new add-on geometry to the standard nose was designed to provide a simplified bonnet feature. This was chosen in order to vary the on-set flow approaching the platoon and also to influence the flow in the gap between test models. As previously found, the close-proximity presence of a following model resulted in significant drag reductions for the lead model due to wake suppression. Based on drag accumulation analyses in CFD, the “shielding” effect provided by the lead model gave a more significant drag reduction on the front of the following model when fitted with the bonnet addition compared to the standard nose. But the beneficial acceleration of the flow around the A-pillars of the following model was negated resulting in small total drag increases. As in previous investigations, one significant observation was that none of the upper-body geometries was found to be optimal in every position and combination of models.</div></div>

A data-driven model based on modal decomposition: application to the turbulent channel flow over an anisotropic porous wall

This article presents a data-driven model based on modal decomposition, applied to approximate the low-order statistics of the spatially averaged wall-shear stress in a turbulent channel flow over a porous wall with two anisotropic permeabilities, producing drag increase or reduction when compared with the case of an isotropic porous wall. The model is comparable to a neural network architecture using a linear map to a classification. To create this model, we use high-order dynamic mode decomposition (DMD) to identify the structures describing the main flow dynamics, and then test different linear combinations of these modes to estimate the time evolution of the stress at the porous interface. The coefficients of the model are obtained by training the model against the results of direct numerical simulations over different time intervals. Depending on the number and the way of combining the DMD modes, the reduced-order models presented can reconstruct the wall-shear stress with relative error smaller than 0.01 % and reproduce its statistical variations for at least 1500 time units with relative error in the standard deviation or the mean smaller than 5 %. The model has also been tested to approximate the statistics of the wall-shear stress over the whole wall, showing that the regeneration of the flow structures can be reproduced by the nonlinear interaction of modes. Finally, considering the DMD modes as communities in a neural network, we examine the influence of the mode-to-mode interaction on the nonlinear flow dynamics, which explains the performance of the different models.

Numerical Investigation of Winglet Aerodynamics and Dimple Effect of NACA 0017 Airfoil for a Freight Aircraft

Drag reduction is an ever-present challenge within the aeronautical engineering industry. This paper presents two substantial wing modifications: the addition of a winglet of a freighter aircraft and a dimpled wing on the NACA 0017 aerofoils. Studies on nine (9) different geometries of dimpled aerofoils were performed against a control model of an aerofoil without any dimple. Computational fluid dynamics (CFD) analysis was performed using two (2) commercial CFD platforms. This paper also explored two novel solutions of aircraft optimisation to mitigate the effects of drag and leading-edge pressure, while increasing the effect of lift. The optimised performance model of a freighter aircraft increased its aerodynamic efficiency. The study found that at take-off velocity of 82 m/s, winglets decreased pressure on the wing by 16.31%, through flow redirection and better flow integration into aerofoils wake. The study also analysed the separation layer and its effect through the appropriate use of the dimple effect. Increased lift effects were observed on a NACA 0017 aerofoil. Despite the low increase in drag of 6% from the modifications, the resultant L/D ratio was highly increased. This study also faced some challenges with validating the model. Hence some validation approaches were taken, and some other approaches suggested for future studies.

Experimental and Numerical Analyses of a Novel Wing-In-Ground Vehicle

The AeroCity is a new form of transportation concept that has been developed to provide high-speed ground transportation at a much lower cost than the existing high-speed railway. Utilizing the Wing-in-Ground (WIG) effect, the AeroCity vehicle does not require complex infrastructures like other contemporary concepts, such as the Hyperloop or Maglev trains. In the current work, the aerodynamic characteristics of the AeroCity vehicle are examined through a Computational Fluid Dynamics (CFD) analysis. The results from the CFD analysis qualitatively match with the findings of wind tunnel experiments. Surface streamlines and boundary layer measurements correspond well with the numerical data. However, the force measurements show a discrepancy. It is found that the separation bubble over the side plates is not captured by the CFD, and this is responsible for an under-prediction of the drag at higher free-stream velocities. The Transition SST model improved the matching between the experiments and numerical simulations. The influence of the moving ground is numerically investigated, and the effect of non-moving ground on the vehicle aerodynamics was found not to be significant. Finally, the inclusion of the track wall is examined. It is found that the merging of the wingtip vortices is responsible for a significant drag increase and, therefore, an alternative track geometry should be investigated.

Modified Trailing Edge Impact on the Aerodynamic Performance of Wind Turbine Airfoil

One of the most important factors affecting wind turbine performance is the airfoil. The impact of the NACA 0012 trailing edge design on airfoil performance is investigated numerically in this paper. Computational fluid dynamics calculations are used to design and simulate the airfoils. The thick trailing edge is inclined to various angles to achieve further improvement in the lift/drag ratio and lift coefficient. The results reveal that, when compared with baseline airfoil, all the designed airfoils demonstrated higher lift coefficients. The lift coefficient increases with the angle of the inclined trailing edge. The maximum lift coefficient improvement inclined airfoil is 74%. In addition, the lift/drag ratio increases with the increase of the inclined angle, and the maximum improvement ratio reaches 39.495% for the inclined airfoil with Ꝋ=15º. Any further increase in the inclined angle decreases the lift/drag ratio as a result of drag increase. This study contributes toward the design of efficient wind turbine airfoils.

Pragmatic Treatment Strategies for Polyaromatic Hydrocarbon Remediation and Anti-biofouling from Surfaces Using Nano-enzymes: a Review.

In this review, two important environmental pollutants have been considered for its potential remediation using microbial-derived nano-enzymes. Firstly, polyaromatic hydrocarbons (PAHs) are one of the major industrial contaminants in the environment due to their ubiquitous occurrence, toxicity, and proclivity for bioaccumulation. Secondly, biofouling due to biofilm-forming organisms that impact tremendous economic and environmental consequences in many industries, especially marine vessels where it causes an increase in hydrodynamic drag, which results in a loss of ship speed at constant power or a power increase to maintain the same speed with higher fuel consumption and emissions into the atmosphere, particularly Green House Gases (GHGs).Among the remediation strategies, biological routes are found to be promising, efficient, and sustainable. Natural ligninolytic enzymes such as MnP, LiP, laccase, peroxidases, and polysaccharide and protein degradative enzymes are found to be highly efficient for PAH degradation and antifouling respectively. However, large-scale usage of these enzymes is difficult due to various reasons like their poor stability, adaptation, and high-cost production of these enzymes. In recent years, the use of nanoparticles, particularly nano-enzymes, is found to be an innovative and synergistic approach to detoxify contaminated areas with concomitant maintenance of enzyme stability.

Near-wake of a yaw-oscillating circular cylinder at subcritical flow

In this experimental study, the near wake of a circular cylinder undergoing yaw oscillations is investigated. The yaw angle during oscillations varies from θ=0o (exposing cylinder directly to crossflow) to 30o at two different Reynolds numbers of 5×103 and 1.5×104. Planar Particle Image Velocimetry measurements are used to study the flow topology in the near-wake region of the yaw-oscillating cylinder for a range of oscillation frequencies, which when expressed non-dimensionally in terms of reduced frequencies (K) vary between K=0.25 to 4. For a cylinder undergoing yaw oscillation, the wake closure length and wake width vary with the phase angle of the oscillation cycle for a given oscillation frequency. At moderate reduced frequencies, the phase-averaged recirculation region is suppressed completely when the cylinder is closer to a certain yaw angle, which was found to be, a yaw angle of θ=15o or above in the return cycle (depending on the value of K). The yaw-oscillating cylinders generally show longer wake closure lengths in their return cycle compared to the equivalent yaw angles in the first half of their oscillation cycle. It is shown that although the wake closure length shows changes depending on the phase in the oscillation cycle for a given oscillation frequency, as the frequency of oscillation is elevated, the vortices generally shed nearer to the surface of the cylinder. Thereby, for moderate reduced frequencies of yaw oscillation, the extent of the yaw-averaged recirculation region downstream of the cylinder reduces considerably as the frequency increases, suggesting an increase in the base suction pressure, which may be speculated to result in a drag increase locally in the measurement plane (at the midspan of the cylinder) in comparison to the static counterpart. For the highest reduced frequency investigated (K=4), the phase-averaged recirculation region was observed to be suppressed completely during all phases of oscillation.

Near wake interactions and drag increase regimes for a square-back bluff body

The three-dimensional near wake of a square-back bluff body in ground proximity is experimentally perturbed by placing a pair of D-shaped obstacles under the body. Five obstacle widths $d$ , from 12 % to 26 % of the height of the body, are used to perform a sensitivity study of the body's pressure drag by varying the relative distance $l$ between the obstacle pair and the base. Two successive drag-sensitive regimes are identified for obstacle-to-base distances $l/d < 2.5$ , where the pressure drag of the body is increased up to 22 %. In different regimes, the flow dynamics measured downstream of the obstacles are found to be very different. When the obstacles are the closest to the base, $l/d<1.5$ , the pressure drag changes of the main body are driven by mean merging between the wakes of the obstacles and of the main body, and scale with $d$ . Contrarily, when the obstacles are located farther from the base, $1.5< l/d<2.5$ , the wakes of the obstacles are isolated from the main body wake. Here the dynamics of the obstacle wake drive the pressure drag changes of the main body, which scale with $d^{2}$ . In both regimes, we measure a mean mass transfer from the wake of the main body to the wakes of the obstacles. This is the main mechanism responsible for the pressure drag changes. Using our results and reference studies describing the effects of base suction on the pressure drag of bluff bodies, a physical model is proposed to explain the contrasting scalings of the pressure drag increase in the different regimes observed in this study.

Linear instability and resonance effects in large-scale opposition flow control

Opposition flow control is a robust strategy that has been proved effective in turbulent wall-bounded flows. Its conventional set-up consists of measuring wall-normal velocity in the buffer layer and opposing it at the wall. This work explores the possibility of implementing this strategy with a detection plane in the logarithmic layer, where control could be feasible experimentally. We apply control on a channel flow at $Re_\tau = 932$ , only on the eddies with relatively large wavelengths ( $\lambda / h > 0.1$ ). Similarly to the buffer layer opposition control, our control strategy results in a virtual-wall effect for the wall-normal velocity, creating a minimum in its intensity. However, it also induces a large response in the streamwise velocity and Reynolds stresses near the wall, with a substantial drag increase. When the phase of the control lags with respect to the detection plane, spanwise-homogeneous rollers are observed near the channel wall. We show that they are a result of a linear instability. In contrast, when the control leads with respect to the detection plane, this instability is inactive and oblique waves are observed. Their wall-normal profiles can be predicted linearly as a response of the turbulent channel flow to a forcing with the advection velocity of the detection plane. The linearity, governing the flow, opens a possibility to affect large scales of the flow in a controlled manner, when enhanced turbulence intensity or mixing is desired.