Shear Intensity Research Articles

Experimental and numerical study of convective heat transfer in-line tube bundle by acoustic action

This paper proposes the acoustic properties acting on the in-line tube bundles heat exchanger and an analysis of the tube bundle gap flow characteristics and convective heat transfer. In contrast to the reported literature, the present study adds the effect of audible sound on the tube array gap flow, in which the Reynolds number for free flow is Re = 2000, sound frequency is f = 100–1000 Hz, and sound pressure level range is SPL = 127–145 dB. In this paper, a numerical calculated turbulence intensity and Reynolds shear stress of the fluid in the tube bundles gap for acoustic frequency and sound pressure level. Moreover, experiments revealed the effect of acoustic properties on convective heat transfer on the surface of the tube bundles. The results show that the average Nussle number increases by almost 1.8 when the acoustic frequency f = 100 Hz is added, and the sound pressure level reaches 145 dB, compared to no acoustic perturbation. The average Nussle number increases by almost 2.1 when the sound pressure level reaches 145 dB with frequency modulation of f = 1000 Hz. Since the relative error is less than 15% between experimental and numerical calculations, acoustic waves are able to enhance convective heat transfer through the tube array. At the same time, the present study serves as a reference for engineering applications.

Can synoptic drivers explain rotor‐area wind conditions and predict energy output?

AbstractSynoptic‐scale weather patterns are an important driver of wind speed at turbine hub height, but wind energy generation is also affected by the wind profile across the rotor. In this research, we use a 6‐year record of hourly profile measurements at the Eolos Wind Research Station in Minnesota, USA, to investigate whether synoptic weather patterns can provide information about rotor‐area characteristics in addition to hub‐height wind speed. We use sea level pressure data from the MERRA‐2 reanalysis to classify synoptic patterns at the Eolos site into 15 synoptic types and use the Eolos wind profile data to create mean hourly and mean monthly values of wind speed and turbulence intensity at hub height (80 m), and wind speed shear, wind direction shear, and the potential temperature gradient across the rotor (30–129 m), for each synoptic type. Using a simple linear regression model, we find that, at monthly time scales, wind speed, turbulence intensity, and wind speed shear across the rotor are the most important variables for predicting monthly wind energy output from the Eolos turbine. Regression models using the original Eolos data and the derived synoptic types capture about 64% and 55% of the variance in monthly energy output, respectively. When fewer than the full 6 years of observations are used to fit the regression model, however, predictions using the synoptic types slightly outperform predictions using the Eolos observations. These results suggest that seasonal energy projections may be enhanced by incorporating wind profile measurements with synoptic‐scale drivers.

Micromechanical analysis of suction pile-granular soil interaction under inclined pulling load: Effect of pulling angle

The micro-mechanism of interaction between the suction pile and granular soil under the inclined pulling load of mooring lines remains unclear. This study investigated suction pile-soil interaction behaviour under an inclined load with different pulling angles using the coupled DEM-FEM. Discontinuity and large deformation occurrences in soil, such as voids, gaps, soil upheaval and collapse, were successfully modelled. The changes in pulling force under different pulling angles were found to stem from the suction pile-soil interaction modes. Additionally, the rotation axes of a suction pile were obtained by examining soil pressure distributions on anchor sides, and the resulting rotation angles of the suction pile were compared with each other based on these axes. The discussion includes a schematic diagram that explains the development of the rotation axes and an analysis of the shear intensity on the anchor surface. Further analysis of a series of typical particle-scale behaviours is presented, finishing with the identification of conclusive mechanical patterns of soil failure. The study suggests that neglecting the pulling angle of mooring lines can result in severely misestimating the pull-out capacity of a suction pile and misjudging the failure pattern of granular soil.

Free-surface undulation and velocity turbulence in shallow undular hydraulic jumps

Undular hydraulic jumps and bores occur in coastal and estuarial regions at small approach Froude numbers and introduce non-uniform evolution of hydraulic properties in the flow direction, affecting the transport and deposition of sediment and other materials. This paper reports an experimental study of relatively wide undular hydraulic jumps generated in a 1.4-m-wide flume, characterized by inflow aspect ratio less than 0.06 and no lateral shockwave crossing at the first standing wave crest. General free-surface shape observations were conducted for a range of Froude numbers between 1.5 and 2.9 and Reynolds numbers between 2.5 × 104 and 1.2 × 105, while detailed free-surface and velocity measurements were performed at longitudinal and transverse cross-sections using acoustic displacement meters (ADMs) and an acoustic Doppler velocimeter (ADV), at five Froude numbers from 1.5 to 1.9. The results highlight complicated relationship of the three-dimensional free-surface characteristics with the variation of Froude number, which exhibits different features at the first two waves and at other sequent waves. The velocity data highlighted unique features of turbulent velocity redistribution at the first wave, including the distributions of turbulence intensity and Reynolds shear stresses. Particular focus on the formation of a “quiet water” zone below the upward-deflected mainstream flow was reported, with presence of instantaneous reversing velocities above the channel bed. The flow pattern analysis was facilitated with mean vorticity characterization. The results reflect that the evolution of undular hydraulic jump with increasing Froude number is a process of gradual turbulence localization towards the first standing wave, and the transition to a breaking hydraulic jump is achieved by the formation of a surface roller at the steepened jump front overwhelming the “resistance” of the bottom “quiet water” zone and forcing a change in the main flow path.

Dynamic kirigami structures for wake flow control behind a circular cylinder

A flow passing through a bluff body can produce Karman shedding vortex streets in its wake flow, resulting in strong unsteady loading and vibration. Existing passive control methods can disturb the wake flow, but are usually effective only under certain conditions and cannot adapt to changing environments due to their fixed topographies. Kirigami structures (the art of paper cutting) demonstrate programable out-of-plane buckling deformation under simple force actuations. By stretching and relaxing these kirigami sheets, an array of tilted surface elements can be easily activated and deactivated on the surface of a bluff body. For the first time, kirigami structures are used to achieve dynamic passive flow control. The control performance on the wake flow of a cylinder is validated in a wind tunnel using particle image velocimetry. Activated kirigami structures can push the shedding vortices further downstream from the cylinder by about four times of the uncontrolled one and reduce peak values of the turbulent intensity and Reynolds shear stress by 70% and 50%, respectively. The control performance is largely dependent on the height and shape of the kirigami structures.

Quantitative assessment of muscle properties in polymyositis and dermatomyositis using high-frequency ultrasound and shear wave elastography

Polymyositis (PM) and dermatomyositis (DM) are two common types of idiopathic inflammatory myopathy and can lead to a poor prognosis and quality of life. We designed this cross-sectional study to investigate the abilities of high-frequency ultrasound (HFUS) and shear wave elastography (SWE) to assess muscle properties in patients with PM and DM and to distinguish healthy muscles from diseased muscles with PM and DM. A total of 60 patients (26 PM cases and 34 DM cases) and 65 matched healthy volunteers were continuously included in the case and control groups, respectively. For the bilateral deltoid, biceps brachii, rectus femoris, and vastus lateralis, the muscle thickness, echo intensity, and longitudinal shear wave velocity (SWV) of all participants were measured using HFUS and SWE. The intra- and interobserver reliability of SWV measurements of patients with PM and DM and the receiver operating characteristic curve for HFUS and SWE for PM and DM were analyzed. Patients with PM and DM had significantly decreased muscle thickness and increased muscle echo intensity compared to healthy controls (P<0.001). The patients' and healthy participants' deltoid, biceps brachii, rectus femoris, and vastus lateralis thickness was 19.75 and 23.00 mm, 20.45 and 22.80 mm, 18.40 and 20.20 mm, and 20.00 and 22.80 mm, respectively. Except for the biceps brachii, the mean SWV in the longitudinal orientation in patients with PM and DM significantly decreased (P<0.01). The mean SWV of the patients' and healthy participants' deltoid, rectus femoris, and vastus lateralis was 2.47 and 2.57 m/s, 1.73 and 1.87 m/s, and 1.57 and 1.77 m/s, respectively. Excellent intra- and interobserver reliability of SWV measurements on the deltoid and rectus femoris of PM and DM patients were found (intraclass correlation coefficient >0.95; P<0.001). The diagnostic performance of echo intensity in lower-extremity proximal muscles for PM and DM was excellent [area under the curve (AUC) >0.9]. The thickness of most muscles displayed moderate diagnostic performance (the AUC ranged from 0.700 to 0.775). The SWV of the vastus lateralis showed a stable performance (AUC =0.741). The combined diagnostic performance of echo intensity and thickness and the combined diagnostic performance of the 3 indicators were relatively high (the AUC ranged from 0.871 to 0.936 and from 0.898 to 0.938, respectively). Muscle thickness and echo intensity showed statistical differences in different disease stages of PM and DM (P'<0.01). HFUS and SWE may serve as imaging biomarkers for the diagnosis of PM and DM by detecting abnormal muscle thinning, enhanced muscle echo intensity, and reduced muscle SWV.

Accounting for Environmental Conditions in Data-Driven Wind Turbine Power Models

Continuous assessment of wind turbine performance is a key to maximising power generation at a very low cost. A wind turbine power curve is a non-linear function between power output and wind speed and is widely used to approach numerous problems linked to turbine operation. According to the current IEC standard, power curves are determined by a data reduction method, called binning, where hub height, wind speed and air density are considered as appropriate input parameters. However, as turbine rotors have grown in size over recent years, the impact of variations in wind speed, and thus of power output, can no longer be overlooked. Two environmental variables, namely wind shear and turbulence intensity, have the greatest impact on power output. Therefore, taking account of these factors may improve the accuracy as well as reduce the uncertainty of data-driven power curve models, which could be helpful in performance monitoring applications. This paper aims to quantify and analyse the impact of these two environmental factors on wind turbine power curves. Gaussian process (GP) is a data-driven, nonparametric based approach to power curve modelling that can incorporate these two additional environmental factors. The proposed technique's effectiveness is trained and validated using historical 10-minute average supervisory control and data acquisition (SCADA) datasets from variable speed, pitch control, and wind turbines rated at 2.5 MW. The results suggest that (i) the inclusion of the additional environmental parameters increases GP model accuracy and reduces uncertainty in estimating the power curve; (ii) a comparative study reveals that turbulence intensity has a relatively greater impact on GP model accuracy, together with uncertainty as compared to blade pitch angle. These conclusions are confirmed using performance error metrics and uncertainty calculations. The results have practical beneficial consequences for O&M related activities such as early failure detection.

A 10-Year Statistic Study on the Tornadoes That Occurred in Jiangsu and Zhejiang Province: Composite Background Environment and Linear Trends

According to a 10-year (from 2007 to 2016) statistical analysis on the tornadoes in China, Jiangsu Province and Zhejiang Province, which share many similar geographical characteristics, experienced 159 (ranked first) and 59 (ranked fifth) tornadoes, respectively. Tornadoes within Jiangsu [i.e., the Jiangsu type (JST)] and those within Zhejiang [i.e., the Zhejiang type (ZJT)] featured notable annual, monthly and diurnal variations, which were remarkably different from each other. Both JST and ZJT showed the largest occurrence frequency (~50% on average) in the afternoon of summer, and the background environments before the formation of these tornadoes were composited to focus on their respective universal features. For the JST, it is found that, the upper-tropospheric divergence and positive geopotential-height anomaly, the middle-tropospheric shortwave trough, warm temperature advection and positive temperature anomaly, and the lower-tropospheric strong southwesterly wind, convergence and cyclonic vorticity all acted as favorable conditions for the convective activities within Jiangsu. For the ZJT, their background environment differed from that of the Jiangsu notably, and the conditions for the tornadoes’ formation were overall more favorable for the JST. Linear trend analyses indicated that, both the annual and seasonal (summer) occurrence of the JST tended to decrease significantly, whereas, those of the ZJT were not significant. For the JST, its occurrence frequency showed a low linear correlation to the variation of the surface temperature, instead, its decreasing frequency was more closely related to the significant weakening in the intensity of the vertical shear of the zonal wind and the updraft helicity within Jiangsu.

Evaluating the Rheo-electric Performance of Aqueous Suspensions of Oxidized Carbon Black

HypothesisThe macroscopic properties of carbon black suspensions are primarily determined by the agglomerate microstructure built of primary aggregates. Conferring colloidal stability in aqueous carbon black suspensions should thus have a drastic impact on their viscosity and conductivity. ExperimentsCarbon black was treated with strong acids following a wet oxidation procedure. An analysis of the resulting particle surface chemistry and electrophoretic mobility was performed in evaluating colloidal stability. Changes in suspension microstructure due to oxidation were observed using small-angle X-ray scattering. Utilizing rheo-electric measurements, the evolution of the viscosity and conductivity of the carbon black suspensions as a function of shear rate and carbon content was thoroughly studied. FindingsThe carboxyl groups installed on the carbon black surface through oxidation increased the surface charge density and enhanced repulsive interactions. Electrostatic stability inhibited the formation of the large-scale agglomerates in favor of the stable primary aggregates in suspension. While shear thinning, suspension conductivities were found to be weakly dependent on the shear intensity regardless of the carbon content. Most importantly, aqueous carbon black suspensions formulated from electrostatically repulsive primary aggregates displayed a smaller rise in conductivity with carbon content compared to those formulated from attractive agglomerates.

Wake Interactions of Two Tandem Semisubmersible Floating Offshore Wind Turbines Based on FAST.Farm

Wake effects commonly exist in offshore wind farms, which will cause a 10–20% reduction of whole power production as well as a 5–15% increase of fatigue loading on the wind turbine main structures. Obviously wake interaction between floating offshore wind turbine (FOWT) is more complicated, and needs careful assessment which is a prerequisite for active wake control (AWC). The primary objective of the present research is to investigate in detail how the wake inflow condition, streamwise spacing, turbulence intensity, and wind shear influence the power performance, platform motion dynamic and structural loading of FOWT. FAST.Farm, developed by the National Renewable Energy Laboratory (NREL), was used for simulating two tandem FOWTs in different conditions. Comparisons were made between FOWTs in different conditions on power performance and platform motion dynamic, which were presented through both time and frequency domain analysis. Damage equivalent loads change in FOWTs interference under typical working conditions were discussed and summarized. Half wake inflow would pose many challenges to the downstream FOWT. These research studies can be incorporated into further offshore wind farm wake models, providing applicable AWC strategies to reduce wake interference effects for higher energy production and for the longer life of FOWT.

Flow behaviour concerning bank stability in the presence of spur dike – A review

Abstract Flow in streams and rivers typically erodes the banks, causing channel bank migration laterally, resulting in loss of nearby land, modification in channel morphology, excessive sediment transport, and water quality degradation. A spur dike is a hydraulic structure placed at the channel bank projecting outward to guide or divert the flow away from the bank, thus protecting it from erosion. The stability of the riverbed and banks is influenced by turbulent characteristics such as three-dimensional velocity distribution, turbulent kinetic energy, Reynolds shear stress, turbulent intensity, and bed shear stress. The researchers found that these turbulence parameters are instrumental in sediment movement along the channel's bed and from its banks. Spurs dikes are a significant river training structure provided along the river bank to protect from erosion. Several aspects related to spur dikes, such as their geometry, physical features, design considerations, flow and scour patterns, etc., are critically reviewed in this paper. Despite the numbers of literature in the field of turbulent characteristics and scour depth around spur dike, the role of vegetation and the effect of seepage around spur dike still remains an unexplored area. These knowledge gaps of spur dikes in field conditions are discussed for future studies.

Direct numerical simulation of turbulent open channel flows at moderately high Reynolds numbers

Well-resolved direct numerical simulations of turbulent open channel flows (OCFs) are performed for friction Reynolds numbers up to $Re_\tau =2000$ . Various turbulent statistics are documented and compared with the closed channel flows (CCFs). As expected, the mean velocity profiles of the OCFs match well with the CCFs in the near-wall region but diverge notably in the outer region. Interestingly, a logarithmic layer with Kárman constant $\kappa =0.363$ occurs for OCF at $Re_\tau =2000$ , distinctly different from CCF. Except for a very thin layer near the free surface, most of the velocity and vorticity variances match between OCFs and CCFs. The one-dimensional energy spectra reveal that the very-large-scale motions (VLSMs) with streamwise wavelength $\lambda _x&gt;3 h$ or spanwise wavelength $\lambda _z&gt;0.5 h$ contribute the most to turbulence intensity and Reynolds shear stress in the overlap and outer layers (where h is the water depth). Furthermore, the VLSMs in OCFs are stronger than those in CCFs, resulting in a slightly higher streamwise velocity variance in the former. Due to the footprint effect, these structures also have significant contributions to the mean wall shear stress, and the difference between OCF and CCF enlarges with increasing $Re_\tau$ . In summary, the free surface in OCFs plays an essential role in various flow phenomena, including the formation of stronger VLSMs and turbulent kinetic energy redistribution.

Reynolds stress modeling of supercritical narrow channel flows using OpenFOAM: Secondary currents and turbulent flow characteristics

In this study, the full Launder, Reece and Rodi pressure-strain model, and nonlinear boundary damping functions were incorporated in OpenFOAM® to simulate the turbulence-driven secondary currents in supercritical narrow channel flows, such as in sediment bypass tunnels. Five simulations were performed under uniform flow conditions covering Froude numbers from 1.69 to 2.56 and aspect ratios (channel width to flow depth) ar from 0.9 to 1.91 to investigate the formation of secondary currents and their impacts on longitudinal velocity, turbulence characteristics, and bed shear stress distribution. The numerical results of the maximum longitudinal velocity and the average shear velocity show marginal deviations, of less than 2.6%, from two-dimensional experimental results acquired under decelerating flow conditions. However, some differences are observed for the secondary currents and for the vertical turbulence intensity and Reynolds shear stress in the outer flow region, especially for cases with higher flow nonuniformity (that can influence the surface perturbation) whose influence is missing in the numerical model. No intermediate vortex is observed for ar = 1.91. However, it develops for lower ar and detaches from the free surface vortex when ar ≤ 1.05. Such vortex bulges the longitudinal velocity contour lines inward and the zone of higher longitudinal velocity narrows and deepens with a decrease in ar. The decrement reduces the magnitude of the normalized maximum secondary velocity. It also affects the bottom vortex which alters the bed shear stress distribution.

A novel laser Doppler anemometer (LDA) for high-accuracy turbulence measurements

High accuracy and dynamic range have been some of the most prominent challenges when it comes to fine-scale turbulence measurements. The current commercial LDA processors, which perform the signal processing of Doppler bursts directly using hardware components, are essentially black boxes and in particular are renown for suffering from practical limitations that reduce the measurement reliability and accuracy. A transparently functioning novel LDA, utilizing advanced technologies and up-to-date hardware and software has therefore been developed to enhance the measurement quality and the dynamic range. In addition, the self-developed software comes with a highly flexible functionality for the signal processing and data interpretation. The LDA setup and the combined forward/side scattering optical alignment (to minimize the effective measuring volume) are described first, followed by a description of the signal processing aspects. The round turbulent jet has been used as the test bed since it presents a wide range of degree of difficulty for the LDA processor (accuracy, dynamic range etc.) across the different radial distances and downstream development. The data are diagnosed for dynamic range in residence and interarrival times, and compared to a typical hardware driven processor. The radial profiles of measured mean streamwise velocity and variance agree well with previous studies of the round jet. The spatial turbulent kinetic energy spectra in the fully developed region perfectly match the expected (and in this region well established) -5/3 power law even for the largest measured distances from the centerline (where shear and turbulence intensity are significant).

Improving the coating and prepressing properties of soybean meal adhesive by constructing a biomimetic topological structure

Developing a soy protein-based (SP) adhesive with robust coating and prepressing properties for broad applications in wood-based panels presents a challenge. In this study, a “bond-stitch” topological structure was constructed in a SP adhesive to improve coating ability and prepressing bond strength by incorporating dopamine-grafted sodium alginate (SD) as stitching materials and zinc sulfate (ZnSO4) into soybean meal–polyamide–epichlorohydrin (SM/PAE) adhesive. Abundant catechol groups on SD enhance the interfacial interaction between the adhesive and wood, and the topological entanglement of SD and the SM/PAE covalent network enhances the cohesion of the adhesive, synergistically endowing the adhesive with excellent prepressing intensity (0.83 MPa) and wet shear strength (1.09 MPa). Simultaneously, the improved initial adhesion and the suitable viscosity result in its excellent coating performance. The combination of ZnSO4 endows the adhesive with satisfactory antibacterial activity and mildew resistance. This method exhibits considerable potential for application in bio-based adhesives, hydrogels, and composites.

Experimental investigations into the effect of urban airflow characteristics on urban air mobility applications

Unmanned Aircraft Systems (UAS) operations in urban environment are significantly challenged by the complex airflow structures and high levels of turbulence owing to the densely built-up regions and the presence of tall buildings. This paper investigates the urban airflow characteristics that are expected to pose significant challenges to the flight of unmanned aircraft systems and impair their aerodynamic stability. Using experimental methods, a 1:400 scale city model was tested in an Atmospheric Boundary Layer (ABL) wind tunnel at various wind incidence angles to capture a representative range of wind speed changes, wind direction changes, wind shear and turbulence intensity flow features. The results can be used as a first step in informing regulations for UAS operations in urban flows, where the most severe flow conditions are those which contribute to develop operational limits. This paper reveals the severity of the flow conditions in representative urban environments, particularly around and between the buildings.

Rayleigh–Bénard instability in the presence of phase boundary and shear

We study the two-dimensional Rayleigh–Bénard instability subject to the combined effects of a solid–liquid phase boundary and shear using linear stability theory and energy analysis. We consider two thermal states of the solid (isothermal and conducting), and two types of shear that can arise in different contexts. When the melting temperature is equal to that held at the top boundary, three instability modes can arise with the increase of Reynolds number Re that characterizes the shear intensity: a boundary mode, a mixed boundary–bulk mode and a bulk flow mode. When the melting temperature lies between the top and the bottom boundaries, the introduction of Couette flow, independent of its intensity, always leads to the mixed mode, whereas the instability with Poiseuille flow is dominated by the bulk flow mode once Re exceeds a critical value, below which the mixed mode dominates. The energy analysis suggests that there exist two mechanisms by which the shear flow affects the system: one is by inhibiting the upward heat flux and another is by absorbing energy from the perturbed hydrodynamic field. These two mechanisms can play totally different roles in different cases. Results in the high-Re regime indicate that, when Re exceeds its classical threshold, i.e. Re = 5772.2 for Poiseuille flow, the Tollmien–Schlichting instability will be dominant in the present system.

Characteristics of very-large-scale motions in gradually varied open-channel flows upstream of a run-of-river dam

The gradually varied open-channel flows (OCF) upstream of a run-of-river (RoR) dam are ubiquitous in natural rivers. In this flow type, the velocity profile shows some similarities to that in uniform open-channel flows, but the turbulence intensity and Reynolds shear stress are slightly greater. However, the presence and properties of very-large-scale motions (VLSMs) in such flows are still unclear. To fill this research gap, time-resolved particle image velocimetry measurements were performed upstream of a modeled RoR dam in an open-channel flume. Based on pre-multiplied spectra analysis, statistical evidence of the presence of VLSMs in the flow type is reported for the first time. The results reveal that although the typical streamwise wavelength of VLSMs in such gradually varied OCF is similar to that in other flows, such as turbulent boundary layers, closed-channel flows, pipe flows, and uniform OCF, the VLSMs in the present gradually varied OCF are stronger and contribute more streamwise turbulent kinetic energy as well as Reynolds shear stress than other flows.

The Shear‐Relative Variation of Inflow Angle and Its Relationship to Tropical Cyclone Intensification

AbstractCharacterizing inflow structure is important to better represent tropical cyclone impacts in numerical models. While much research has considered the impact of storm translation on the distribution of inflow angle, comparatively less research has examined its distribution relative to the environmental wind shear. This study analyzes data from 3,655 dropsondes in 44 storms to investigate the radial and shear‐relative distribution of surface inflow angle. Emphasis is placed on its relationship with intensity change. The results show that the radial variation in the inflow angle is small and not significantly dependent on the shear magnitude or intensity change rate. In contrast, the azimuthal distribution of the inflow angle shows a significant asymmetry, with the amplitude of the asymmetry increasing with shear magnitude. The maximum inflow angle is located in the downshear side. The degree of asymmetry is larger in the outer core than in the eyewall. Intensifying storms have a smaller degree of asymmetry than steady‐state storms under moderate shear.

A high-throughput integrated biofilm-on-a-chip platform for the investigation of combinatory physicochemical responses to chemical and fluid shear stress.

Physicochemical conditions play a key role in the development of biofilm removal strategies. This study presents an integrated, double-layer, high-throughput microfluidic chip for real-time screening of the combined effect of antibiotic concentration and fluid shear stress (FSS) on biofilms. Biofilms of Escherichia coli LF82 and Pseudomonas aeruginosa were tested against gentamicin and streptomycin to examine the time dependent effects of concentration and FSS on the integrity of the biofilm. A MatLab image analysis method was developed to measure the bacterial surface coverage and total fluorescent intensity of the biofilms before and after each treatment. The chip consists of two layers. The top layer contains the concentration gradient generator (CGG) capable of diluting the input drug linearly into four concentrations. The bottom layer contains four expanding FSS chambers imposing three different FSSs on cultured biofilms. As a result, 12 combinatorial states of concentration and FSS can be investigated on the biofilm simultaneously. Our proof-of-concept study revealed that the reduction of E. coli biofilms was directly dependent upon both antibacterial dose and shear intensity, whereas the P. aeruginosa biofilms were not impacted as significantly. This confirmed that the effectiveness of biofilm removal is dependent on bacterial species and the environment. Our experimental system could be used to investigate the physicochemical responses of other biofilms or to assess the effectiveness of biofilm removal methods.