Flow Velocity Shear Research Articles

Fluid–structure interaction simulation for studying hemodynamics and rupture risk of patient-specific intracranial aneurysms

Purpose The role of regional hemodynamics in intracranial aneurysms (IAs) hemodynamics and rupture risk has been widely discussed based on numerical models over the past decades. The aim of this paper is to investigate hemodynamics and rupture risk with a complicated IA model. Methods Fluid-structure interaction (FSI) simulations were performed to quantify the hemodynamic characteristics of the established IA models. Hemodynamic parameters, including wall shear stress (WSS), flow velocity, and flow pattern, were calculated and analyzed. Results In this paper, the risk assessment of intracranial aneurysms focuses on the mechanical properties of blood flow and blood vessel walls. Vortex flow and concentrated impact field during blood flow play a decisive role in the rupture and development of aneurysms. The uneven distribution of wall shear stress on the vessel wall has a great influence on growth and rupture. By observing the simulation results of rigid walls, risks can be predicted efficiently and accurately. Conclusions This paper focuses on the relationship between hemodynamics and ruptures risk with a double intracranial aneurysms disease mode and provides a new perspective on the treatment of intracranial aneurysms.

Variations in hydraulic efficiency of the subglacial drainage landsystem control surging and streaming regimes of outlet glaciers

AbstractSurging and streaming of glaciers are modulated by meltwater availability and pressure which controls mechanical coupling at their beds. Using laboratory-scale experimental modelling and palaeoglaciological mapping, we explore how subglacial drainage landsystems control meltwater drainage efficiency and ice flow velocities for terrestrial-based ice lobes resting on flat horizontal and permeable beds. Two end-members regimes, surging and streaming, appear in our experiments. The surge regime is characterised by a rapid increase of drainage efficiency through development of tunnel valleys and their tributaries, thus reducing the duration of ice flow speed-up events by lowering water pressures and increasing ice-bed coupling. Tunnel valleys connected to ice lobe margins, submarginal thrust moraines, reduced ice lobe extensions and ephemeral shear margins are the most distinctive characteristics of this regime. The stream regime is characterised by disconnected channels of smaller dimensions unable to evacuate all the meltwater: this prolonged drainage inefficiency leads to sustained high ice flow velocity and steady shear margins. Small and rectilinear meltwater channels devoid of tributaries, often disconnected from ice lobe margins, and lineation swarms are diagnostic of this regime.

Secondary island induced during magnetic reconnection by an external sub-Alfvénic shear flow

Secondary tearing instability induced associated with sub-Alfvénic shear flow during magnetic reconnection processes is investigated using a compressible resistive MHD model. Compared to the without shear flow case, it is found that a secondary island can be built up during the reconnection process with an external sub-Alfvénic shear flow. For further investigation, we also found that the built-up island is not developed so larger due to the pairs of discontinuities formed in the inflow region of the reconnection. For the fixed initial asymptotic shear flow velocity v0, there existing a critical value λvc fastest to excite the secondary island. The critical value λvc may vary with different v0. Although, there is a significant gap for reconnection rates between the simulation results and observations, it can be deduced that the discontinuities can be formed in the situations with sheared flows associated with the magnetic reconnection. The results can be applied to interpret the multiple-X lines reconnections and discontinuities observations at the Earth's dayside magnetopause and magnetotail.

Cerebral hemodynamics during atrial fibrillation: Computational fluid dynamics analysis of lenticulostriate arteries using 7 T high-resolution magnetic resonance imaging.

Atrial fibrillation (AF) is the most common cardiac arrhythmia, inducing irregular and faster heart beating. Aside from disabling symptoms-such as palpitations, chest discomfort, and reduced exercise capacity-there is growing evidence that AF increases the risk of dementia and cognitive decline, even in the absence of clinical strokes. Among the possible mechanisms, the alteration of deep cerebral hemodynamics during AF is one of the most fascinating and least investigated hypotheses. Lenticulostriate arteries (LSAs)-small perforating arteries perpendicularly departing from the anterior and middle cerebral arteries and supplying blood flow to basal ganglia-are especially involved in silent strokes and cerebral small vessel diseases, which are considered among the main vascular drivers of dementia. We propose for the first time a computational fluid dynamics analysis to investigate the AF effects on the LSAs hemodynamics by using 7 T high-resolution magnetic resonance imaging (MRI). We explored different heart rates (HRs)-from 50 to 130 bpm-in sinus rhythm and AF, exploiting MRI data from a healthy young male and internal carotid artery data from validated 0D cardiovascular-cerebral modeling as inflow condition. Our results reveal that AF induces a marked reduction of wall shear stress and flow velocity fields. This study suggests that AF at higher HR leads to a more hazardous hemodynamic scenario by increasing the atheromatosis and thrombogenesis risks in the LSAs region.

Hydrodynamic Analysis and Cake Erosion Properties of a Modified Water-Based Drilling Fluid by a Polyacrylamide/Silica Nanocomposite during Rotating-Disk Dynamic Filtration.

In this study, the potential of using a polyacrylamide-silica nanocomposite (PAM-S) to control the filtration properties of bentonite water-based drilling muds under different salinity conditions was evaluated. Static filtration tests under low-pressure/low-temperature (LPLT) conditions accompanied by rheological measurements have been carried out to analyze the role of silica nanoparticles (NPs) and nanocomposites (NCs) in the base fluid properties. Moreover, high-pressure/high-temperature (HPHT) static filtration was also investigated to evaluate the thermal stability of PAM-S. Afterward, dynamic filtration has been conducted in a filtration cell equipped with an agitating system with a disk-type impeller to investigate the hydrodynamic and formation of a filter cake under shear flow conditions. Fluid flow velocity and wall shear stress (WSS) distribution over the filter cake were analyzed using an exact 3D computational fluid dynamic (CFD) simulation. A transparent filtration cell with a camera was used to accurately record the fluid flow field inside the filter press and validate the CFD results. The obtained results indicated that adding silica NPs at a concentration of less than 2 wt % increases the fluid loss due to reducing rheological properties such as yield point. While silica NPs could not significantly change the mud properties, the experimental results showed that, under both LPLT and HPHT conditions, the PAM-S NC could reduce the total filtration loss by 70% at a low concentration of 0.75 wt %. Moreover, during dynamic filtration, the results indicated that there is a linear relationship between the cake thickness and the inverse of WSS at different operating pressures. However, no correlation could be found between predeposited mud cake erosion and WSS. At a rotating disk speed of 1000 rpm, more than 60% of the predeposited mud cake was eroded after 30 min for a saline mud sample while for the NC-treated mud sample cake erosion is considerably reduced and reaches up to 20% at 1.5 wt % PAM-S.

Evaluate the hemodynamic factors' effects on stenosed arteries with the Carreau model

One of the main causes of death is atherosclerosis so, in this work, two models of stenosed arteries have been executed numerically to assess the hemodynamic effects caused by flow disruptions. Using Computational Fluid Dynamics (CFD) to provide information to the public, particularly surgeons, and assist them in reducing the risk of stenosis. Star-CCM+ software was used to perform CFD techniques such as steady, turbulent, and non-Newtonian (Carreau) and was applied at two different flow rate conditions. Using the blood flow velocity, vorticity, strain rate, and wall shear stress for identifying the plaque-affected section of the arteries, the results showed that in the stenosed areas there is a high blood flow velocity due to the smaller lumen diameter, and a recirculation region was also identified immediately after the stenosed part, resulting in increased plaque development.

Numerical investigation of VIV responses of the flexible riser system modelled as tensioned cable subjected to shear flow

The crossflow vortex-induced vibration (VIV) responses of the tensioned cable subjected to the sheared flow velocity profile are investigated numerically using the wake oscillator model. A comparative study is carried out on the VIV response characteristics between the tensioned cable and beam with an aspect ratio (L/D) of 3000. The study was conducted on tensioned cable having different L/D of 2000 and 3000 achieved by varying both diameter and length of the cable. The effect of top tension on the RMS crossflow displacement responses is investigated. The RMS crossflow displacement response is not sensitive to the boundary conditions for the flexible cylinder modeled as a tensioned cable. In contrast, the RMS crossflow displacement response of the lower L/D flexible cylinder modeled as a beam is sensitive to boundary conditions. The standing wave response pattern is observed for the beam with L/D of 500. The standing and traveling wave response patterns are combined for the tensioned cable with L/D = 500. Unlike finite tensioned beams, the higher mode responses are obtained even in the lower aspect ratio for tensioned cables.

Critical selection of shear sheltering in electroconvective flow from chaotic to steady state

Ion and water are transported by electroconvection near permselective membranes, resulting in complex phenomena associated with the flow–fines interaction. Sheltering the flow chaos by the shear flow is a common strategy in plasma fluids and has recently been successfully applied to control ionic fluids. The paper herein reveals the critical selection of shear velocity regarding the fluid from a chaotic to a steady state through numerical and theoretical analyses. For the shear sheltering, the dimensionless Debye length ${\lambda _D}$ with varying channel height is introduced to achieve a comprehensive discussion of the factors and laws affecting the shear vortex state. Based on an analysis of the vortex driving mechanism, the scaling of the slip velocity ${u_s}\sim {(\lambda _D^{ - 1}\Delta {\phi ^4})^{1/3}}$ is recommended as the critical selection factor for the steady and chaotic state under a fixed shear flow velocity, which involves the dimensionless Debye length ${\lambda _D}$ and voltage difference $\Delta \phi $ . Furthermore, for ionic fluid control by shear flow, a critical shear velocity ${U_{HPC}}$ is proposed to distinguish the electroconvective flow from a chaotic state to a steady state. When the shear flow velocity ${U_{HP}} > {U_{HPC}}$ , the shear flow shelters chaos, and the scaling law is also recommended for the regulation of the critical shear flow velocity ${U_{HPC}}$ jointly by ${\lambda _D}$ and $\Delta \phi $ . The analysis is confirmed by direct numerical simulation and existing experimental data (J. Fluid Mech, vol. 813, 2017, pp. 799–823). This work provides a more comprehensive physical insight for shear sheltering and affects the design of electromembrane microfluidics.

A mathematical model that describes the relation of low-density lipoprotein and oxygen concentrations in a stenosed artery

The cellular activities of the endothelium layer between lumen and intima are significantly linked to the origin of the disease atherosclerosis. Three stages of atherosclerosis were investigated in this study (40%-mild, 50%-modest, and 60%-acute) concerning the coronary arterial segment. The essence of the hemodynamic factors like flow velocity, pressure, and wall shear stress has been investigated, as well as the interrelationships between them. At all degrees of stenosis, the biophysical relationship between convection-diffusion of low-density lipoproteins (LDL) and convection-diffusion of oxygen in the bloodstream is investigated. The Finite Element Methods (FEM) are used to solve the modeled partial differential equation systems. The method adopted is numerical in nature providing accurate graphical solutions to the framed systems. The physical effects of the deposition of LDL on the arterial wall, like a decrease in the diameter of the lumen, and toughening of the walls, are analyzed through the evaluation of the physical parameters. The study revealed that the deposition of LDL molecules in the post stenotic region leads to the depletion of oxygen in the region leading to the rapid dysfunctioning of the endothelial layer of the lumen-intima boundary.

Role of patient-specific blood properties in computational fluid dynamics simulation of flow diverter deployed cerebral aneurysms.

BACKGROUND: Hemodynamics and their clinical outcome of cerebral aneurysms treated with flow diverter (FD) stents have thus far been investigated using computational fluid dynamics (CFD) simulations. Although human blood is characterized as a non-Newtonian patientspecific fluid, non-patient-specific blood properties (PSBP) were applied in most extant studies.OBJECTIVE: To investigate the hemodynamic effects caused by PSBPs in aneurysms treated with FD stents.METHODS: We measured blood properties (density and viscosity) for 12 patients who underwent FD stent deployment. We conducted CFD simulations with the measured PSBPs and non-PSBPs quoted from previous studies. The average blood flow velocity and wall shear stress within the aneurysms were calculated and two simulation patterns were compared.RESULTS: The velocity and wall shear stress changed by 2.93% and 3.16% on average, respectively, without an FD stent deployed. Conversely, with the FD stents deployed, the change rates increased to 11.1% and 9.06% on average, respectively.CONCLUSIONS: The change in hemodynamic parameters if PSBPs are considered, may not be negligible when conducting CFD simulations of FD stent deployed aneurysms To obtain an adequate hemodynamic environment for cerebral aneurysms with FD stents deployed, it is recommended to use PSBPs for CFD simulations.

Ultrasonic Dispersion Influence on the Rheological Properties of Double Emulsion Food Systems with a High Content of Polyunsaturated Fatty Acids

The author rheological parameters research of dual food emulsion systems with different oil base composition obtained by ultrasonic dispersion aims at determining the use prospects and studying the structural features. A man obtained flow curves for the double food emulsion systems under research by the rotational rheometry at temperatures of 20 °C and 30 °C. The emulsion systems demonstrated a non-Newtonian behavior, manifested as a change in viscosity with a shear flow velocity change. A comparative viscosity analysis of emulsion systems samples subjected to the ultrasonic dispersion for 10, 15 and 20 minutes showed that the dispersion duration did not have the significant effect on their rheological parameters. The flow curve of a sample with linseed and sunflower oils as a basis differs from the flow curves of samples with ginger–sunflower and mustard–sunflower oils combinations, which are characterized by a transition to the Newtonian flow regime at higher shear velocities. At the same time, the double emulsion systems viscosity does not depend on the blend composition. The temperature has no significant influence on the rheological parameters of most of the studied emulsion systems. The viscosity index was higher in a sample with linseed and sunflower oils as a base at a temperature of 20 °C at the same low values of shear velocities than at a temperature of 30 °C. The decrease in the dispersed structure strength along with an increase in temperature explains that.

The Role of Hemodynamics through the Circle of Willis in the Development of Intracranial Aneurysm: A Systematic Review of Numerical Models.

Background: The role of regional hemodynamics in the intracranial aneurysmal formation, growth, and rupture has been widely discussed based on numerical models over the past decades. Variation of the circle of Willis (CoW), which results in hemodynamic changes, is associated with the aneurysmal formation and rupture. However, such correlation has not been further clarified yet. The aim of this systematic review is to investigate whether simulated hemodynamic indices of the CoW are relevant to the formation, growth, or rupture of intracranial aneurysm. Methods: We conducted a review of MEDLINE, Web of Science, and EMBASE for studies on the correlation between hemodynamics indices of the CoW derived from numerical models and intracranial aneurysm up to December 2020 in compliance with PRISMA guidelines. Results: Three case reports out of 1046 publications met our inclusion and exclusion criteria, reporting 13 aneurysms in six patients. Eleven aneurysms were unruptured, and the state of the other two aneurysms was unknown. Wall shear stress, oscillatory shear index, von-Mises tension, flow velocity, and flow rate were reported as hemodynamic indices. Due to limited cases and significant heterogeneity between study settings, meta-analysis could not be performed. Conclusion: Numerical models can provide comprehensive information on the cerebral blood flow as well as local flow characteristics in the intracranial aneurysm. Based on only three case reports, no firm conclusion can be drawn regarding the correlation between hemodynamic parameters in the CoW derived from numerical models and aneurysmal formation or rupture. Due to the inherent nature of numerical models, more sensitive analysis and rigorous validations are required to determine its measurement error and thus extend their application into clinical practice for personalized management. Prospero registration number: CRD42021125169.

Research on Preparation of Three-Component Composite Fiber with Complex Cross-Sectional Pattern.

In this work, a preparation method of three-component composite fibers with complex cross-sectional patterns was proposed, and the fibers with complex cross-sectional patterns were fabricated using melt spinning. Initially, inspired by the shape of a fishbone, a spinning pack with three-component melt channels was designed for spinning fibers with a “fishbone” cross-sectional pattern. Then, the numerical simulation of the melt flow in the channels of the spinning pack was performed using Polyflow software. The spinning pack structure was optimized by analyzing the flow velocity distribution and shear rate distribution of different components within the spinning pack channels. The results showed that smaller velocity fluctuations contribute to the clarity of the cross-sectional pattern. Thereafter, the spinning experiments were carried out based on the optimized spinning pack. The effect of the flow ratio between the three components on the cross-sectional pattern was discussed, and the three-component composite fibers with a clear “fishbone” cross-sectional pattern were obtained. Finally, in order to further study the effectiveness of the complex cross-sectional pattern fiber preparation proposed in this paper, another spinning pack for fibers with an “H-shaped” cross-sectional pattern was designed according to the aforementioned method, and spinning experiments were carried out. The SEM images of the cross-sections of fibers with “fishbone” and “H-shaped” cross-sectional patterns were obtained, verifying the feasibility of the method proposed in this paper. Moreover, the fibers with complex cross-sectional patterns obtained by this method have a certain anti-counterfeiting effect and can also be blended with other yarns to obtain fabrics with anti-counterfeiting effects.

Abstract No. 147 Comparison of Celect inferior vena cava filter thrombus incidence based on filter position at time of filter retrieval

Some authors have used computational modeling to identify the juxtarenal position as the optimal placement location for Celect IVC filters due to the presence of high shear stress and flow velocity. Others have called into question the assumptions made in the computational model. The purpose of our study is to evaluate the relationship between presence of trapped Celect IVC filter thrombus and juxtarenal and infrarenal filter positioning at retrieval.

Laser coagulation and hemostasis of large diameter blood vessels: effect of shear stress and flow velocity

Photocoagulation of blood vessels offers unambiguous advantages to current radiofrequency approaches considering the high specificity of blood absorption at available laser wavelengths (e.g., 532 nm and 1.064 µm). Successful treatment of pediatric vascular lesions, such as port-wine stains requiring microvascular hemostasis, has been documented. Although laser treatments have been successful in smaller diameter blood vessels, photocoagulation of larger sized vessels is less effective. The hypothesis for this study is that a primary limitation in laser coagulation of large diameter blood vessels (500–1000 µm) originates from shear stress gradients associated with higher flow velocities along with temperature-dependent viscosity changes. Laser (1.07 µm) coagulation of blood vessels was tested in the chicken chorio-allantoic membrane (CAM). A finite element model is developed that includes hypothetical limitations in laser coagulation during irradiation. A protocol to specify laser dosimetry is derived from OCT imaging and angiography observations as well as finite element model results. Laser dosimetry is applied in the CAM model to test the experimental hypothesis that blood shear stress and flow velocity are important parameters for laser coagulation and hemostasis of large diameter blood vessels (500–1000 µm). Our experimental results suggest that shear stress and flow velocity are fundamental in the coagulation of large diameter blood vessels (500–1000 µm). Laser dosimetry is proposed and demonstrated for successful coagulation and hemostasis of large diameter CAM blood vessels.

Hemodynamic and Structural Comparison of Human Fetal Heart Development Between Normally Growing and Hypoplastic Left Heart Syndrome-Diagnosed Hearts.

Congenital heart defects (CHDs) affect a wide range of societies with an incidence rate of 1.0–1.2%. These defects initiate at the early developmental stage and result in critical health disorders. Although genetic factors play a role in the formation of CHDs, the occurrence of cases in families with no history of CHDs suggests that mechanobiological forces may also play a role in the initiation and progression of CHDs. Hypoplastic left heart syndrome (HLHS) is a critical CHD, which is responsible for 25–40% of all prenatal cardiac deaths. The comparison of healthy and HLHS hearts helps in understanding the main hemodynamic differences related to HLHS. Echocardiography is the most common imaging modality utilized for fetal cardiac assessment. In this study, we utilized echocardiographic images to compare healthy and HLHS human fetal hearts for determining the differences in terms of heart chamber dimensions, valvular flow rates, and hemodynamics. The cross-sectional areas of chamber dimensions are determined from 2D b-mode ultrasound images. Valvular flow rates are measured via Doppler echocardiography, and hemodynamic quantifications are performed with the use of computational fluid dynamics (CFD) simulations. The obtained results indicate that cross-sectional areas of the left and right sides of the heart are similar for healthy fetuses during gestational development. The left side of HLHS heart is underdeveloped, and as a result, the hemodynamic parameters such as flow velocity, pressure, and wall shear stress (WSS) are significantly altered compared to those of healthy hearts.

Study of Electrostatic Ion-Cyclotron Waves in Magnetosphere of Uranus

In this manuscript, the method of characteristics particle trajectories details used and the dispersion relation for the ionosphere of Uranus were being used to investigate electrostatic ion-cyclotron waves with parallel flow velocity shear in the presence of perpendicular inhomogeneous DC electric field and density gradient. The growth rate has been calculated using the dispersion relation. Electric fields parallel to the magnetic field transmit energy, mass, and momentum in the auroral regions of the planetary magnetosphere by accelerating charged particles to extremely high energies. The rate of heating of plasma species along and perpendicular to the magnetic field is also said to be influenced by the occurrence of ion cyclotron waves and a parallel electric field in the acceleration area.

Contrast Agent-Free Assessment of Blood Flow and Wall Shear Stress in the Rabbit Aorta using Ultrasound Image Velocimetry.

Blood flow velocity and wall shear stress (WSS) influence and are influenced by vascular disease. Their measurement is consequently useful in the laboratory and clinic. Contrast-enhanced ultrasound image velocimetry (UIV) can estimate them accurately but the need to inject contrast agents limits utility. Singular value decomposition and high-frame-rate imaging may render contrast agents dispensable. Here we determined whether contrast agent-free UIV can measure flow and WSS. In simulation, accurate measurements were achieved with a signal-to-noise ratio of 13.5 dB or higher. Signal intensity in the rabbit aorta increased monotonically with mechanical index; it was lowest during stagnant flow and uneven across the vessel. In vivo measurements with contrast-free and contrast-enhanced UIV differed by 4.4% and 1.9% for velocity magnitude and angle and by 9.47% for WSS. Bland–Altman analysis of waveforms revealed good agreement between contrast-free and contrast-enhanced UIV. In five rabbits, the root-mean-square errors were as low as 0.022 m/s (0.81%) and 0.11 Pa (1.7%). This study indicates that with an optimised protocol, UIV can assess flow and WSS without contrast agents. Unlike contrast-enhanced UIV, contrast-free UIV could be routinely employed.

Abstract TMP6: Computational Hemodynamic Analysis Of Intra-Aneurysmal Effects Due To Flow Diverter Stent Deployment Conformation

Introduction: Inflow blockage of aneurysms treated with flow diverter stents is dependent on the deployed braid angle (ϕ)—the angle between the yarns which comprise the stent braids and the longitudinal axis of the braid. We utilized computational fluid dynamic (CFD) analysis to examine the effects of braid angle on intra-aneurysmal hemodynamic parameters associated with long-term treatment success. Methods: Two flow diverter stents measuring 3.5 mm in diameter, each containing 88 strands with ϕ = 10° and ϕ = 35° were constructed and deployed into a patient model of an internal carotid artery saccular aneurysm containing pulsatile blood flow. Intra-aneurysmal flow velocity, pulsatility index (PI), turbulence, vorticity, and wall shear stress (WSS) parameters were obtained and compared for the two braid angles. Results: Reducing ϕ from 35° to 10° resulted in -2.59%, -1.92%, and -1.41% changes in systolic bulk velocity, and -1.79%, +0.57%, and -1.65% changes in PI at the aneurysm neck, body, and dome respectively. Vorticity changes were insignificant. High turbulence extending through the aneurysm neck peaked approximately 0.04 s later in systole, and was located closer to the parent vessel outlet when ϕ = 10°. Elevated intra-aneurysmal WSS was concentrated at the neck and body on the side of the parent vessel outlet for both ϕ = 10° and ϕ = 35°. Regions of WSS in excess of 10 Pa stretched higher into the aneurysm body when ϕ = 35°. Conclusion: Stenting at a lower ϕ resulted in higher blockage of flow and better reduction of WSS for initiating and facilitating long term intra-aneurysmal thrombosis. CFD analysis incorporating precise reconstruction of the stent deployment conformation into patient models can provide detailed visualization of flow parameters for assessing potential treatment efficacy throughout the diagnostic and treatment phases of patient care.

Flow and wake characteristics associated with riparian vegetation patches: Results from field‐scale experiments

AbstractRiparian vegetation patches growing on river banks and floodplains influence in‐channel and overbank hydromorphological processes. The current knowledge on patch‐scale hydrodynamics is largely based on laboratory flume experiments with simplified vegetation. The aim of this study is to provide new understanding of the flow and wake characteristics for real riparian vegetation patches based on field‐scale experiments with natural willows, in order to inform hydromorphological and ecological modelling. The focus was placed on the effects of foliage as the main driver of the seasonal changes in vegetation and on the influence of the flexibility‐induced reconfiguration on the flow in the wake and around the patches. The patch drag, defined by its flow blockage factor, was increased by 3.0–4.4 times by the presence of foliage and decreased by up to 60% because of the streamlining and reconfiguration of foliage with increasing flow velocity. Such large changes in the patch drag altered the flow and wake characteristics, affecting the onset of a patch‐scale vortex street. Seasonality and flexibility modified the patch sheltering effect, that is, the magnitude of velocity, turbulent kinetic energy, and bed shear stress reduction in the wake, relative to the background level. In the presence of foliage, mean flow velocity and bed shear stress in the wake were reduced on average by ~50% and ~70%, respectively. The sheltering effect was lower for the leafless conditions than for the foliated conditions. For the foliated cases, the spatial extents of the over‐depth and the near‐bed sheltered region were on average 1.5 and 1.8 times larger than in the corresponding leafless cases, respectively. Overall, seasonal changes in vegetation and flexibility‐induced mechanisms were identified as key controls for the flow associated with patches of riparian vegetation, with major implications on developing models for predicting hydromorphological processes and the potential to preserve and create habitats.