Outer Units Research Articles

A single-feed circularly polarized antenna with a low vertical profile and hemispherical axial-ratio beam coverage

ABSTRACT A novel wide axial-ratio beamwidth (ARBW) circularly polarized (CP) antenna with a single layer substrate fed by a single probe is proposed. It consists of an inner annular slotted radiator containing eight outer sector units with arc branches, a ground plane, and eight grounded vias. The antenna has an ARBW covering the upper hemisphere and has a low vertical profile. The ultra-hemispherical ARBW is formed by ingeniously merging the endfire omnidirectional CP radiation pattern with the boresight CP radiation pattern. The two radiation patterns can be excited by a central coaxial probe without an additional feeding network. An antenna prototype of dimensions 1.15 × 1.15 × 0.02 (λ 0 3) is fabricated and measured to validate the design concept. Measured results show that the impedance bandwidth of the proposed antenna is 2.0% (3.328–3.394 GHz) and the 3 dB axial ratio (AR) bandwidth is 1.3% (3.332–3.374 GHz). The 3 dB AR beamwidth can cover more than 217° and the maximum gain is 0.79 dBic at 3.35 GHz. A good agreement between the simulated and measured results is obtained.

Customized 3D‐printed heterogeneous porous titanium scaffolds for bone tissue engineering

AbstractBone defect is a common clinical disease. Due to the uncertainty of trauma or infection areas, customized size features are often required for bone substitutes. By inspiration of the natural bone structure, this study designs porous scaffolds with a biomimetic design perspective by using different inner and outer pore units. The outer pore units adopt body‐centered cubic (BCC) structure to simulate the weight‐bearing function of human cortical bone, while inner pore units using I‐Wrapped Package structure, a kind of three periods minimum surface, to obtain a good permeability and simulates the inner layer of cancellous bone. To further regulate the overall modulus of the scaffold within the range of natural bone modulus in the human body, the scaffold was designed to axial gradient structure. Compression experiments were conducted, and the results indicated that when the volume fraction linearly increased from 20% to 50%, the Young's modulus was close to the cortical bone modulus in the human body. In vitro cell experiments further proved that osteoblasts have good cellular activity and spreading morphology on the surface of this scaffold. The customized 3D‐printed heterogeneous porous titanium scaffold has great application potential in bone tissue engineering.

Investigation of Sidewall and Reynolds Number Effects in a Ribbed Square Duct

This paper presents a comprehensive three-dimensional Direct Numerical Simulation (DNS) investigation of flow characteristics over a roughened wall in a duct, exploring bulk Reynolds number variations from 4400 to 13,200 and considering the influence of side walls. Notably, a significant increase in friction factor highlights heightened resistance to flow due to surface roughness, emphasizing the importance of considering surface conditions in engineering applications. The study reveals three recirculation zones in the streamwise direction, indicating intricate separation phenomena caused by the interaction between the ribbed wall and the flow. Furthermore, the presence of sidewalls creates two major vortices perpendicular to the flow direction, highlighting the complexity of the vortical structures in this configuration, crucial for predicting flow behavior and optimizing system performance. The study demonstrates that the influence of the Reynolds number on these vortices is not well-scalable with respect to outer units, in contrast with respect to smooth ducts. Investigating side-wall effects, increased turbulent production rate, and non-equilibrium turbulence along the side walls highlight the sensitivity of turbulent stresses to Reynolds number and side-wall proximity. In conclusion, the paper provides novel insights into the interplay between Reynolds numbers, roughened surfaces, and boundary conditions in turbulent flows, laying a foundation for a deeper understanding of the flow in duct with high roughness.

New oospecies of Spheroolithidae from the Upper Cretaceous in the Laiyang Basin, Shandong Province, China

Five deformed dinosaur eggs are newly discovered from the Upper Cretaceous Jiangjunding Formation in the Laiyang Basin, Shandong Province, China. A new oospecies of Spheroolithidae, Spheroolithus phacelus, was erected based on the spheroid eggs and the developed cone-shaped eggshell unit assemblages. Radial sections of S. phacelus show the inner cone-shaped eggshell units, the middle columnar eggshell units and the outer bush-like eggshell units. Numerous cone-shaped eggshell unit assemblages and large gaps between them are developed in the inner part, columnar eggshell units and small pores emerge in the middle part, and branches of eggshell units appear in the outermost part, forming bush-like microstructures. Spheroolithidae is a typical oofamily of East Asia consisting of Spheroolithus spheroides, S. chiangchiungtingensis, S. quantouensis, S. oosp. and Paraspheroolithus irenensis, which mainly distributed in the Upper Cretaceous of China, South Korea, Japan and Mongolia. The discovery of S. phacelus provides new fossil materials of oogenus Spheroolithus in Spheroolithidae and expands the palaeogeographic distribution of Spheroolithidae in East Asia, which may be eggs of hadrosauroid. The age of these deformed dinosaur eggs could be presumed to be the middle Late Cretaceous (Coniacian–Campanian).

Phenoxy Group-Containing Asymmetric Non-Fullerene Acceptors Achieved Higher VOC over 1.0 V through Alkoxy Side-Chain Engineering for Organic Solar Cells.

Alkoxy side chain engineering on the β-position of the thienothiophene units of Y6 derivatives plays a vital role in improving photovoltaic performances with simultaneously increasing open-circuit voltage (Voc) and fill factor (FF). In this work, we prepared a series of asymmetric non-fullerene acceptors (NFAs) by introducing alkoxy side chains and phenoxy groups on the state-of-the-art Y6-derivative BTP-BO-4F. For the comparison, 2O-BO-4F with a symmetric alkoxy side chain on the outer thiophene units and BTP-PBO-4F with an asymmetric N-attached phenoxy alkyl chain on the pyrrole ring are synthesized from BTP-BO-4F. Thereafter, we construct four asymmetric NFAs by introducing different lengths of linear/branched alkoxy chains on the β-position of the thienothiophene units of BTP-PBO-4F. The resulting NFAs, named L10-PBO, L12-PBO, B12-PBO, and B16-PBO (L = linear and B = branched alkoxy side chains), are collectively called OR-PBO-series. Unexpectedly, all OR-PBO NFAs exhibit strong edge-on molecular packing and weaker π-π interactions in the film state, which diminish the charge transfer in organic solar cell (OSC) devices. As a consequence, the optimal devices of OR-PBO-based binary blends show poor photovoltaic performances [power conversion efficiency (PCE) = 6.52-9.62%] in comparison with 2O-BO-4F (PCE = 12.42%) and BTP-PBO-4F (PCE = 15.30%) reference blends. Nevertheless, the OR-PBO-based binary devices show a higher Voc and smaller Vloss. Especially, B12-PBO- and B16-PBO-based devices achieve Voc over 1.00 V, which is the highest value of Y-series OSC devices to the best of our knowledge. Therefore, by utilizing higher Voc of OR-PBO binary blends, B12-PBO and B16-PBO are incorporated into the PM6:BTP-PBO-4F-based binary blend and fabricated ternary devices. As a result, the PM6:BTP-PBO-4F:B12-PBO ternary device delivers the best PCE of 15.60% with an increasing Voc and FF concurrently.

Direct numerical simulation-based vibroacoustic response of plates excited by turbulent wall-pressure fluctuations

We use direct numerical simulation to study the vibroacoustic response of an elastic plate in a turbulent channel at $Re_\tau$ of 180 and 400 for three plate boundary conditions and two materials – synthetic rubber and stainless steel. The fluid–structure–acoustic coupling is assumed to be one-way coupled, i.e. the fluid affects the solid and not vice versa, and the solid affects the acoustic medium and not vice versa. The wall pressure consists of intermittent large-amplitude fluctuations associated with the near-wall, burst-sweep cycle of events. For stainless steel plates, displacement has similar large-amplitude peak events due to comparable time scales of plate vibration and near-wall eddies. For synthetic rubber plates, large-amplitude displacement fluctuations are observed only near clamped or simply supported boundaries. Away from boundaries, plate displacement resembles an amplitude-modulated wave, and no large-amplitude events are observed. We discuss displacement and acoustic pressure spectra over different frequency ranges. For frequencies much smaller than the first natural frequency, the product of plate-averaged displacement spectrum and bending stiffness squared collapses with Reynolds number and plate material in outer units. At high frequencies, displacement and acoustic pressure spectra scale better in inner units, and the scaling depends on the type of damping. For synthetic rubber plates, the spectra display an overlap region that collapses in both outer and inner units. Soft plate deformation displays a range of length scales. However, stiff plate deformation does not exhibit a similar range of scales and resembles plate mode shapes. The soft plate has two distinct deformation structures. Low-speed, large deformation structures with slow formation/break-up time scales are found away from boundaries. High-speed, small deformation structures with fast formation/break-up time scales formed due to boundary reflections exist near the boundaries.

The Wall-Jet Region of a Turbulent Jet Impinging on Smooth and Rough Plates

The study reports direct numerical simulations of a turbulent jet impinging onto smooth and rough surfaces at Reynolds number Re = 10,000 (based on the jet mean bulk velocity and diameter). Surface roughness is included in the simulations using an immersed boundary method. The deflection of the flow after jet impingement generates a radial wall-jet that develops parallel to the mean plate surface. The wall-jet is structured into an inner and an outer layer that, in the limit of infinite local Reynolds number, resemble a turbulent boundary layer and a free-shear flow. The investigation assesses the self-similar character of the mean radial velocity and Reynolds stresses profiles scaled by inner and outer layer units for varying size of the roughness topography. Namely the usual viscous units u_tau and delta _nu are used as inner layer scales, while the maximum radial velocity u_m and its wall-normal location z_m are used as outer layer scales. It is shown that the self-similarity of the mean radial velocity profiles scaled by outer layer units is marginally affected by the span of roughness topographies investigated, as outer layer velocity and length reference scales do not show a significantly modified behavior when surface roughness is considered. On the other hand, the mean radial velocity profiles scaled by inner layer units show a considerable scatter, as the roughness sub-layer determined by the considered roughness topographies extends up to the outer layer of the wall-jet. Nevertheless, the similar character of the velocity profiles appears to be conserved despite the profound impact of surface roughness.

Linearised Reynolds-averaged predictions of secondary currents in turbulent channels with topographic heterogeneity

A rapid predictive tool based on the linearised Reynolds-averaged Navier–Stokes equations is proposed in this work to investigate secondary currents generated by streamwise-independent surface topography modulations in turbulent channel flow. The tool is derived by coupling the Reynolds-averaged momentum equation to the Spalart–Allmaras transport equation for the turbulent eddy viscosity, using a nonlinear constitutive relation for the Reynolds stresses to capture correctly secondary motions. Linearised equations, describing the steady flow response to arbitrary surface modulations, are derived by assuming that surface modulations are shallow. Since the equations are linear, the superposition principle holds and the flow response induced by an arbitrary modulation can be obtained by combining appropriately the elementary responses obtained over sinusoidal modulations at multiple spanwise length scales. The tool permits a rapid exploration of large parameter spaces characterising structured surface topographies previously examined in the literature. Here, channels with sinusoidal walls and with longitudinal rectangular ridges are considered. For sinusoidal walls, a large response is observed at two spanwise wavelengths scaling in inner and outer units respectively, mirroring the amplification mechanisms in turbulent shear flows observed from transient growth analysis. For longitudinal rectangular ridges, the model suggests that the analysis of the response and the interpretation of the topology of secondary structures is facilitated when the ridge width and the gap between ridges are used instead of other combinations proposed in the literature.

Gyroscope-Structured Triboelectric Nanogenerator for Harvesting Multidirectional Ocean Wave Energy.

Wave motion in the ocean can generate plentiful energy, but it is difficult to harvest wave energy for practical use because of the low frequency and random directional characteristics of wave motion. In this paper, a gyroscope-structured triboelectric nanogenerator (GS-TENG) is proposed for harvesting multidirectional ocean wave energy. Its inner and outer generation units can operate independently in different directions, and they all adopt the friction mode of surface contact. While realizing noninterference multidirectional energy harvesting, the power generation area is increased. In the experiments, under acceleration of 6 m/s2 with variations in excitation angle, the GS-TENG can output direct currents of 0.8-3.2 μA, and the open-circuit voltages of the inner and outer generation units can reach 730 and 160 V, respectively. When the devices are networked and placed in the water, the electrical energy generated by the GS-TENGs can enable commercial thermometers to operate normally. The attenuation of direct-current output by the GS-TENG in the experiment of 30 days in water is about 8%, which verifies the good durability of the device in the water environment. Therefore, the GS-TENG has excellent application prospects in the wave energy harvesting field.

Exact Eddy-Viscosity Equation for Turbulent Wall Flows—Implications for Computational Fluid Dynamics Models

For turbulent channel flow, pipe flow, and zero-pressure gradient boundary layer, Heinz yielded recently analytical formulas for the eddy viscosity as a product of a function of (the wall-normal distance scaled in inner units) and a function of (the same scaled in outer units). By calculating the eddy-viscosity turbulent diffusion term, an exact high-Reynolds-number equation with one production and two dissipation terms is constructed for those flows. One dissipation term is universal, peaks near the wall, and scales mainly with . The second, smaller one, is flow dependent, peaks in the wake, and scales mainly with . The production term is flow dependent, peaks in between, and scales similarly. The universal dissipation term implies a length scale analogous to the von Karman length scale used in the scale-adaptive simulation models of Menter. This length scale also appears in the production term. This confirms the relevance of these length scales. An asymptotic analysis of all terms in the budget in the limit of infinite Reynolds numbers is provided. This yields a test bench of existing Reynolds-averaged Navier–Stokes models with a similar equation. It is shown that some models, e.g., the one of Spalart and Allmaras, do not respect the flow physics: they display a production peak in the near-wall region. The most promising model, a scale-adaptive simulation model, is modified. As a step forward toward a solution to the wall damping problem, the equation of our model behaves much more correctly in the near-wall region.

Decomposition of the mean friction drag on an NACA4412 airfoil under uniform blowing/suction

The application of drag-control strategies on canonical wall-bounded turbulence, such as periodic channel and zero- or adverse-pressure-gradient boundary layers, raises the question on how to distinguish consistently the origin of control effects under different reference conditions. We employ the RD identity (Renard & Deck, J. Fluid Mech., vol. 790, 2016, pp. 339–367) to decompose the mean friction drag and investigate the control effects of uniform blowing and suction applied to an NACA4412 airfoil at chord Reynolds numbers $Re_c=200\,000$ and $400\,000$ . The connection of the drag reduction/increase by using blowing/suction with the turbulence statistics (including viscous dissipation, turbulence kinetic energy production and spatial growth of the flow) across the boundary layer, subjected to adverse or favourable pressure gradients, is examined. We found that the inner and outer peaks of the contributions associated with the friction-drag generation show good scaling with either inner or outer units, respectively. They are also independent of the Reynolds number, control scheme and intensity of the blowing/suction. The small- and large-scale structures are separated with an adaptive scale-decomposition method, namely the empirical mode decomposition (EMD), which aims to analyse the scale-specific contribution of turbulent motions to friction-drag generation. Results unveil that blowing on the suction side of the airfoil is able to enhance the contribution of large-scale motions and to suppress that of small scales; however, suction behaves contrarily. The contributions related to cross-scale interactions remain almost unchanged with different control strategies.

Heteroatom-doped Clar's goblet: Tunable magnetic order and programmable spin logic gate

Nanographene exhibits manifold magnetic orders depending on its topology. The Clar's goblet, envisioned 50 years ago and synthesized recently, is an emblematic nanographene with an antiferromagnetic ground state induced by topological frustration. Inspired by the significant interest in the designer magnetic order of nanographene, we studied the tunable magnetic order in heteroatom-doped Clar's goblet. Interestingly, the antiferromagnetic to ferromagnetic transition is found in doped Clar's goblet by varying the doping positions. A large exchange-coupling strength of 77 meV is realized in a Clar's goblet doped by two nitrogen atoms. The spin directions and distribution at the connecting atoms determine the magnetic order and exchange-coupling strength. Moreover, the spin logic gate based on Clar's goblet can be converted from XOR (XAND) gate into OR (AND) gate by doping the outer units with nitrogen atoms. The heteroatom-doped nanographene with tunable magnetic order provides a platform for spintronic devices with controllable functions.

Use of space, active and resting behaviour in fattening rabbits (Oryctolagus cuniculus) housed in a combi park system: A case study

AbstractIn this case study, a housing system for rabbits (Oryctolagus cuniculus) was developed, complying with the new German Welfare Regulation, and evaluated on-farm with regard to the rabbits’ behaviour during four fattening periods. The housing system was characterised by the large group size of fatteners (maximum 65 animals per group, 12 animals per m2) due to the merging of six former single units for does and their litters, post-weaning. A large elevated platform, a box with a roof (small elevated platform), a tube and gnawing materials were made available per unit. The aim being to assess the suitability of the housing system for rabbits with regard to animal welfare, based on behavioural analyses. Therefore, the use of space by the rabbits (n = 247) was investigated by video analysis (instantaneous scan sampling) during daytime. Additionally, the individual behaviour of 20 focal rabbits in different locations was assessed by continuous sampling. Results showed that rabbits preferred to huddle together in the outer units in the first weeks post-weaning. The highest animal densities were found under and in front of the large and on the small platforms. The large platforms were visited increasingly from the 10th fattening day onwards. Elevated platforms supported resting and comfort behaviours. Non-elevated open-top areas enabled upright positions and locomotor behaviours. Aggression and stereotypic behaviours rarely occurred. We conclude that the housing system supported species-specific behaviour and seemed to cater for the needs of rabbits in terms of welfare. Nevertheless, further investigation is needed to ascertain the effects on animal health and performance.

Molecular level insight into the solvation of cellulose in deep eutectic solvents.

Deep eutectic solvents as sustainable and new-generation solvents show potential in the field of cellulose dissolution. Although these novel materials are tested for numerous industrial, environmental, and medical applications, little is known about the structural features of cellulose interacting with deep eutectic solvents. In this work, the interplay of cellulose is studied in two deep eutectic solvents: choline acetate mixed with urea and choline chloride mixed with urea using classical molecular dynamics simulations. Dissolution of cellulose in the studied liquids was not observed to be in agreement with experimental work from the literature. However, a slight swelling in the chloride, as compared to the acetate-based solvent, is apparent. A possible rationale might be found in the stronger hydrogen bonding of the chloride anion compared to the acetate anion with the hydrogen atoms of the cellulose. Moreover, chloride approaches the outer glucose units comparatively more, which could be interpreted as the onset of entering and thus dissolving the cellulose as was previously observed. Specific hydrogen bonds between all units are analyzed and discussed in detail.

Switching resonance character within merocyanine stacks and its impact on excited-state dynamics

Summary In this study, the optical properties and excited-state dynamics of the unique self-assembled donor-acceptor (DA) merocyanine dye stacks from dimer up to octamer, prepared via dipole-dipole interactions, are reported in terms of coherent exciton dynamics and formation of an excimer-like state. Our findings are based on the steady-state absorption/emission, time-resolved fluorescence, and transient absorption (anisotropy) measurements, including wavepacket analysis and quantum mechanical calculations. Coherent exciton of torsional motions-restricted dye stacks rapidly localizes into the weakly emissive excimer-like state, by shortening the inter-moiety distance and changing the bond-length alternation pattern. The inner merocyanine moiety, having two neighboring units, has a reversed resonance character (non-polar (N) Z) in the ground state. This difference has led to two conclusions: (1) tetramers and octamers exhibit different features of excimer-like state than the dimer, and (2) octamers exhibit slower localization dynamics due to the enhanced homogeneity (six inner-moieties) compared with tetramers (two inner moieties).

Laminar–Turbulent Intermittency in Annular Couette–Poiseuille Flow: Whether a Puff Splits or Not

Direct numerical simulations were carried out with an emphasis on the intermittency and localized turbulence structure occurring within the subcritical transitional regime of a concentric annular Couette–Poiseuille flow. In the annular system, the ratio of the inner to outer cylinder radius is an important geometrical parameter affecting the large-scale nature of the intermittency. We chose a low radius ratio of 0.1 and imposed a constant pressure gradient providing practically zero shear on the inner cylinder such that the base flow was approximated to that of a circular pipe flow. Localized turbulent puffs, that is, axial uni-directional intermittencies similar to those observed in the transitional circular pipe flow, were observed in the annular Couette–Poiseuille flow. Puff splitting events were clearly observed rather far from the global critical Reynolds number, near which given puffs survived without a splitting event throughout the observation period, which was as long as outer time units. The characterization as a directed-percolation universal class was also discussed.

Decomposition of the mean friction drag in adverse-pressure-gradient turbulent boundary layers

From an energy budget perspective, the decomposition of mean friction drag in adverse-pressure-gradient turbulent boundary layers is conducted, obtaining contributions associated with dissipation, production, and convection across the boundary layer. In the wall-normal distributions of the decomposed constituents, positions of inner peaks are well scaled in viscous units, whereas outer peaks scale in outer units, regardless of Reynolds number and pressure-gradient magnitude.

Clinical Application of Carving Template With 3D Reconstruction Technique for Personalized and Precise Treatment of Traumatic Ear Defects.

We explored the clinical application of a 3-dimensional (3D) digital reconstruction technique for personalized and precise traumatic ear defect treatment. A 3D scanner was used to obtain 3D images of the unaffected ear. The data were converted into an ear contour model through mirroring using the software, and imported to a rapid prototyping 3D printer to construct an ipsilateral ear model. For treating different types of ear defect patients with individualized treatment programs, the defective ear model was constructed with individualized autogenous costal cartilage carving. We constructed ipsilateral ear defect models in 16 cases and rebuilt the auricular with >10 outer ear substructure units, maintaining a stable cranial angle. At the 6-month follow-up, the reconstructed ear was similar to the unaffected one, and the patient satisfaction was high. Based on a paired t test, the differences in the width of both auricles was statistically significant, with P values of 0.023, respectively. The differences in the P values of the auricle length, circumference and height, at 0.261, 0.333, and 0.197, respectively, were not statistically significant. Compared to the model utilizing the traditional 2D film template of the ear, the 3D reconstruction technology was more intuitive and stereoscopic, and the personalized ear reconstruction was accurate. Thus, 3D digital technology can avail the most suitable personalized treatment for various traumatic ear defects. It can assist in precisely engraving the reconstructed cartilage stent and objectively analyzing the postoperative results. The therapeutic effect was significant.

Bismuth minerals from the intragranitic La Elsa NYF pegmatite, Potrerillos granite, Argentina: Monitors of fluid evolution from magmatic to hydrothermal stage

ABSTRACTThe NYF La Elsa pegmatite forms a subcircular, ∼30 m long, ∼20 m wide body enclosed in the parental Potrerillos granite, Las Chacras-Potrerillos batholith, Argentina. The pegmatite has a typical zonal internal structure with a volumetrically significant quartz core and pods of magmatic fluorite. Along with biotite, mostly in the outer units, tourmaline (schorl, fluor-schorl) is common to abundant in most pegmatite units. Accessory minerals include common strongly hematitized ilmenite and rare euhedral crystals of bismuthinite, up to 2 cm long, occurring at the transition between the blocky zone and the quartz core. The bismuthinite was significantly replaced by bismutite I according to the reaction Bi2S3(s) + CO2(aq) + 6O2(aq) + 3H2O(l) = Bi2CO3O2(s) + 3H2SO4(aq). Subsequently, bismutite I was replaced by bismutite II and kettnerite. The former requires an influx of Ca and F and its formation can be characterized by the reaction Bi2CO3O2(s) + 2Ca2+(aq) + 2F–(aq) + CO32–(aq) = 2CaBiCO3OF(s). At the late hydrothermal stages bismutite was replaced by clinobisvanite/pucherite during influx of V according to the reaction Bi2CO3O2s + 2H3VO4(aq) = 2BiVO4(s)+ CO2(aq) + 3H2O(l). All Bi minerals are close to the ideal formulae with only minor Pb and ±Cu in bismuthinite and its secondary products. The crystallization sequence of Bi minerals is magmatic bismuthinite (S2–) → early hydrothermal bismutite I (CO32–) → medium stage bismutite II + kettnerite (CO32–, F–) → late stage clinobisvanite, pucherite (VO43–). Pegmatite-derived early subsolidus fluids were enriched in CO2, which was confirmed by confocal Raman microspectroscopy of fluid inclusions in quartz and caused breakdown of bismuthinite to bismutite. Calcium and F, necessary for kettnerite formation, were released during alteration of magmatic fluorite at acidic conditions. Vanadium was supplied by meteoritic H2O enriched in elements from altered magmatic minerals (biotite, ilmenite), either from the pegmatite or from the host granite.

Selective opposition-like control of large-scale structures in wall-bounded turbulence

We investigate the effect of controlling large-scale, logarithmic-layer turbulent structures, which have a characteristic size and aspect ratio that scale with the distance from the wall. The aim is to quantify the effect of suppressing these structures while leaving the near-wall turbulent dynamics unaltered. By affecting only the logarithmic-layer structures, it might be possible to isolate their contribution to the drag from that of the other scales in the flow. We conduct direct numerical simulations of turbulent channel flows at friction Reynolds number ReT ?s 500-1000 and artificially remove certain streamwise and spanwise wavelengths of the wall-normal velocity across a range of heights. The wavelengths chosen depend on the target height (and size) of the structures that we wish to target. When these wavelengths are removed, we observe a positive, outward shift of the mean velocity profile above the target height, due to a local reduction in Reynolds shear stress, and a subsequent increase in viscous stress. Our preliminary results suggest that this shift in the mean velocity profile scales in outer units.