Magnitude Of Flow Velocity Research Articles

Role of large scale flow features on cycle-to-cycle variations of spark-ignited flame-initiation and its transition to turbulent combustion

This study investigates the influence of large-scale flow features, including flow structure and velocity magnitude, on the early-burn period variability in a homogenous-charge spark-ignited engine fueled with premixed propane-air mixture. Particle image velocimetry and in-cylinder pressure measurement data from a previous study - were processed to enable simultaneous flow characterization and flame-front tracking as well as apparent heat-release analysis. By combining probability analysis of flame development with conditional sampling of fast and slow early-burn cycles using 10% fuel mass fraction burned, it is shown that an undesirable flow structure produces an asymmetric flame development at the initial flame growth period. This asymmetric flame structure persists through the whole initial-to-turbulent transition period until the flame becomes fully turbulent. The undesirable flow condition is characterized by large-scale convective flows near spark plug rather than flows that lead to increased flame spread in multiple directions. The simultaneous flow and flame characterization enables the quantifications of flame-front propagation speed, unburned fuel-air mixture velocity ahead of flame front and local burning velocity at flame surface. Here the local burning velocity is referred to as laminar or turbulent flame speed. A simplified approach is introduced to derive integrated values for these quantities per crank-angle-degree, enabling the quantitative comparison of the trend-wise difference in these integrated metrics between fast and slow early-burn cycles. It is revealed that for the transition period, the CCV in the velocity magnitude of unburned fuel-air mixture ahead of the flame front accounts for nearly 50% to the variability of flame propagation speed. The burning velocity provides the remaining source of the flame propagation variability in this period. The flame propagation variations in the initial flame growth and fully turbulent periods are smaller than those in the transition period and are primarily dependent on the variability of large-scale flow features.

MRI analysis to map interstitial flow in the brain tumor microenvironment.

Glioblastoma (GBM), a highly aggressive form of brain tumor, is a disease marked by extensive invasion into the surrounding brain. Interstitial fluid flow (IFF), or the movement of fluid within the spaces between cells, has been linked to increased invasion of GBM cells. Better characterization of IFF could elucidate underlying mechanisms driving this invasion in vivo. Here, we develop a technique to non-invasively measure interstitial flow velocities in the glioma microenvironment of mice using dynamic contrast-enhanced magnetic resonance imaging (MRI), a common clinical technique. Using our in vitro model as a phantom “tumor” system and in silico models of velocity vector fields, we show we can measure average velocities and accurately reconstruct velocity directions. With our combined MR and analysis method, we show that velocity magnitudes are similar across four human GBM cell line xenograft models and the direction of fluid flow is heterogeneous within and around the tumors, and not always in the outward direction. These values were not linked to the tumor size. Finally, we compare our flow velocity magnitudes and the direction of flow to a classical marker of vessel leakage and bulk fluid drainage, Evans blue. With these data, we validate its use as a marker of high and low IFF rates and IFF in the outward direction from the tumor border in implanted glioma models. These methods show, for the first time, the nature of interstitial fluid flow in models of glioma using a technique that is translatable to clinical and preclinical models currently using contrast-enhanced MRI.

Analysis of an Evaporating Sessile Droplet on a Non-Wetted Surface

We investigate evaporation of a sessile droplet on a non-wetted surface in the framework of diffusion-limited and quasi-steady evaporation. We extend previous models and numerically solve Laplace equation for the diffusion of liquid vapor into ambient. We propose a unified, simple and accurate expression of the evaporation mass flux valid for 90° ≤ θ ≤ 180°, where θ is the equilibrium contact angle. In addition, using the derived expression of the evaporation mass flux, we propose a simple and accurate expression of the evaporation mass rate for a non-wetted surface, which does not exhibit singularity at θ = 180°. Finally, using the scaling analysis, the expression of the evaporation mass flux is utilized to estimate the direction and magnitude of the characteristic evaporation-driven flow velocity inside the droplet on a non-wetted surface. The predicted flow direction is found to be consistent with the previous measurements.

2D imaging of helium ion velocity in the DIII-D divertor

Two-dimensional imaging of parallel ion velocities is compared to fluid modeling simulations to understand the role of ions in determining divertor conditions and benchmark the UEDGE fluid modeling code. Pure helium discharges are used so that spectroscopic He+ measurements represent the main-ion population at small electron temperatures. Electron temperatures and densities in the divertor match simulated values to within about 20%–30%, establishing the experiment/model match as being at least as good as those normally obtained in the more regularly simulated deuterium plasmas. He+ brightness (HeII) comparison indicates that the degree of detachment is captured well by UEDGE, principally due to the inclusion of E×B drifts. Tomographically inverted Coherence Imaging Spectroscopy measurements are used to determine the He+ parallel velocities which display excellent agreement between the model and the experiment near the divertor target where He+ is predicted to be the main-ion species and where electron-dominated physics dictates the parallel momentum balance. Upstream near the X-point where He+ is a minority species and ion-dominated physics plays a more important role, there is an underestimation of the flow velocity magnitude by a factor of 2–3. These results indicate that more effort is required to be able to correctly predict ion momentum in these challenging regimes.

Aneurysmal Parent Artery-Specific Inflow Conditions for Complete and Incomplete Circle of Willis Configurations.

Hemodynamics are thought to play a role in intracranial aneurysm growth and rupture. Computational fluid dynamics is frequently performed to assess intra-aneurysmal hemodynamics, using generalized flow waveforms of healthy volunteers as inflow boundary conditions. The purpose of this study was to assess differences in inflow conditions for different aneurysmal parent artery locations and variations of circle of Willis configurations. In a series of 96 patients with 103 aneurysms, velocity measurements were acquired using 2D phase-contrast MR imaging perpendicular to the aneurysmal parent arteries in the circle of Willis. Circle of Willis configurations were inspected for variations using multiple overlapping thin-slab-acquisition MRAs. Flow rates, velocity magnitudes, and pulsatility indices were calculated for each parent artery location in subgroups of complete and incomplete circle of Willis configurations. Flow rates, velocity magnitudes, and pulsatility indices were significantly different among aneurysmal parent arteries. Incomplete circle of Willis configurations were observed in 24% of the cases. Significantly lower basilar artery flow rates were observed in configurations with hypoplastic P1 segments. Significantly higher A1 flow rates were observed in configurations with a hypoplastic contralateral A1 segment. Inflow conditions vary substantially between aneurysmal parent arteries and circle of Willis configurations. We have created a collection of parent artery-specific inflow conditions tailored to the patient-specific circle of Willis configuration that can be used in future computational fluid dynamics studies analyzing intra-aneurysmal hemodynamics.

Preparation and Study of PDMS Material

PDMS (polydimethylsiloxane) has provided number of advantages in recent years has its applications in drug delivery system, dry electrodes and other microfluidic applications. PDMS has also gained its importance as it is easy to prepare and also biocompatible. In this work the PDMS is made to PDMS solid by processing the powder and the material is characterized using SEM (Scanning Electron Microscopy) and Raman Analysis. The characterizations were tested to prove the biocompatibility of the PDMS by carrying the tests in normal sample and sterilized sample. The conductivity of the material was studied for different proportion of binding agent used. Simulations were carried in COMSOL Multiphysics to study the relation between volume flow rate, velocity magnitude and pressure drop in the PDMS micro channel. The simulation results showed the linear relations between the studied variables. The results of the characterization showed the prepared PDMS was in optimum condition and can be used for biomedical applications. The PDMS hydrophilic nature was reduced after preparing the PDMS solid so that it can be coated with metals for electrode and micro channel applications

Local Lorentz force and ultrasound Doppler velocimetry in a vertical convection liquid metal flow

We report velocity measurements in a vertical turbulent convection flow cell that is filled with the eutectic liquid metal alloy gallium-indium-tin by the use of local Lorentz force velocimetry (LLFV) and ultrasound Doppler velocimetry (UDV). We demonstrate the applicability of LLFV for a thermal convection flow and reproduce a linear dependence of the measured force in the range of micronewtons on the local flow velocity magnitude. Furthermore, the presented experiment is used to explore scaling laws of the global turbulent transport of heat and momentum in this low-Prandtl-number convection flow. Our results are found to be consistent with theoretical predictions and recent direct numerical simulations.

Spiral Flow Phantom for Ultrasound Flow Imaging Experimentation.

As new ultrasound flow imaging methods are being developed, there is a growing need to devise appropriate flow phantoms that can holistically assess the accuracy of the derived flow estimates. In this paper, we present a novel spiral flow phantom design whose Archimedean spiral lumen naturally gives rise to multi-directional flow over all possible angles (i.e., from 0° to 360°). Developed using lost-core casting principles, the phantom geometry comprised a three-loop spiral (4-mm diameter and 5-mm pitch), and it was set to operate in steady flow mode (3 mL/s flow rate). After characterizing the flow pattern within the spiral vessel using computational fluid dynamics (CFD) simulations, the phantom was applied to evaluate the performance of color flow imaging (CFI) and high-frame-rate vector flow imaging. Significant spurious coloring artifacts were found when using CFI to visualize flow in the spiral phantom. In contrast, using vector flow imaging (least-squares multi-angle Doppler based on a three-transmit and three-receive configuration), we observed consistent depiction of flow velocity magnitude and direction within the spiral vessel lumen. The spiral flow phantom was also found to be a useful tool in facilitating demonstration of dynamic flow visualization based on vector projectile imaging. Overall, these results demonstrate the spiral flow phantom's practical value in analyzing the efficacy of ultrasound flow estimation methods.

Vector Flow Visualization of Urinary Flow Dynamics in a Bladder Outlet Obstruction Model

Voiding dysfunction that results from bladder outlet (BO) obstruction is known to alter significantly the dynamics of urine passage through the urinary tract. To non-invasively image this phenomenon on a time-resolved basis, we pursued the first application of a recently developed flow visualization technique called vector projectile imaging (VPI) that can track the spatiotemporal dynamics of flow vector fields at a frame rate of 10,000 fps (based on plane wave excitation and least-squares Doppler vector estimation principles). For this investigation, we designed a new anthropomorphic urethral tract phantom to reconstruct urinary flow dynamics under controlled conditions (300 mm H2O inlet pressure and atmospheric outlet pressure). Both a normal model and a diseased model with BO obstruction were developed for experimentation. VPI cine loops were derived from these urinary flow phantoms. Results show that VPI is capable of depicting differences in the flow dynamics of normal and diseased urinary tracts. In the case with BO obstruction, VPI depicted the presence of BO flow jet and vortices in the prostatic urethra. The corresponding spatial-maximum flow velocity magnitude was estimated to be 2.43 m/s, and it is significantly faster than that for the normal model (1.52 m/s) and is in line with values derived from computational fluid dynamics simulations. Overall, this investigation demonstrates the feasibility of using vector flow visualization techniques to non-invasively examine internal flow characteristics related to voiding dysfunction in the urethral tract.

Response of unconfined turbidity current to relay‐ramp topography: insights from process‐based numerical modelling

AbstractThis natural‐scale experimental study combines structural modelling of soft‐linked normal‐fault relays with a CFD (computational fluid dynamics) numerical simulation of a range of unconfined turbidity currents overrunning the relay‐system topography. The flow, released from an upslope inlet gate 2000‐m wide and 50‐m to 100‐m high, rapidly expands and adjusts its thickness, velocity and sediment load to the substrate slope of 1.5°. A lower initial sediment concentration or smaller thickness renders the quasi‐steady flow slower and its sediment‐transport capacity lower. A 3D pattern of large interfering Kelvin‐Helmholtz waves causes fluctuations of the local flow velocity magnitude and sediment concentration. Four zones of preferential sediment deposition are recognized: a near‐gate zone of abrupt flow expansion and self‐regulation; a flow‐transverse zone on the counter‐slope of fault footwall edges; a flow‐transverse zone at the fault‐scarp toes and a similar transverse zone near the crest of the hanging wall counter‐slopes. The sand deposited on the counter‐slope tends to be re‐entrained and fed back to the current by a secondary reverse underflow. The spatial extent and sediment accumulation capacity of depozones depend upon the released current volume. The impact of relay system on an overrunning current depends upon the fault separation distance and stage of tectonic evolution. An early‐stage relay system, with small vertical displacement and little overlap of faults, is bypassed by the current with minimum flow disturbance and no pronounced deposition. An advanced‐stage system, with greater fault displacement and overlap, gives a similar hydraulic effect as a single fault segment if the fault separation is small. If the separation is relatively large, the flow tends to be internally redirected sideways from the ramp into the hanging wall synclinal depressions. Since normal‐fault relays are common features in extensional basins, the study bears important implications for turbiditic slope‐fan models and for the spatial sand prediction in subsurface exploration of faulted submarine slopes.

Dynamic stability of viscoelastic plates under axial flow by differential quadrature method

PurposeCantilever plates subject to axial flow can lose stability by flutter and properties such as viscoelasticity and laminar friction affect dynamic stability. The purpose of the present study is to investigate the dynamic stability of viscoelastic cantilever plates subject to axial flow by using the differential quadrature method.Design/methodology/approachEquation of motion of the viscoelastic plate is derived by implementing Kelvin-Voigt model of viscoelasticity and applying inverse Laplace transformation. The differential quadrature method is employed to discretize the equation of motion and the boundary conditions leading to a generalized eigenvalue problem. The solution is verified using the existing results in the literature and numerical results are given for critical flow velocitiesFindingsIt is observed that higher aspect ratios lead to imaginary part of third frequency becoming negative and causing single-mode flutter instability. It was found that flutter instability does not occur at low aspect ratios. Moreover the friction coefficient is found to affect the magnitude of critical flow velocity, however, its effect on the stability behaviour is minor.Originality/valueThe effects of various problem parameters on the dynamic stability of a viscoelastic plate subject to axial flow were established. It was shown that laminar friction coefficient of the flowing fluid increases the critical fluid velocity and higher aspect ratios lead to single-mode flutter instability. The effect of increasing damping of viscoelastic material on the flutter instability was quantified and it was found that increasing viscoelasticity can lead to divergence instability.

An experimental study of the wake of a model wind turbine using phase-averaging

The wake of a model wind turbine with a rotor diameter of 0.9 m has been investigated at the design condition (tip speed ratio = 6) in a closed return wind tunnel with a cross-section of 1.8 by 2.7 m. The three bladed rotor was operated in a low turbulence intensity uniform flow. Velocity data were obtained in the wake using a four-wire hot-wire probe at 18 radial traverses from x/D=0.22 to 5. All three components of the velocity vector were resolved instantaneously for a wide range of flow angles and velocity magnitudes. In addition to time averaged data, phase-averages with respect to rotor position have been used to extract periodic phase-averaged motions from the flow. In this way the downstream development of the tip vortices was extracted. The phase-averaging method allows the local phase-averaged and turbulent parts of the stresses associated with the vortical motion to be studied, as well as their production terms. The results show that the periodic phase-averaged structures initially contains most of the turbulent kinetic energy and dominate the edge of the wake. The helical vortex structures interact and pair-up, merge and finally breaks up within x/D=3. From this point the phase-averaged motion is lost and the radial transport of momentum across the wake is seen to increase significantly. By x/D=5 the large scale diffusion has removed the sharp edge of the wake that was characteristic in the initial region, and developed the approximately Gaussian velocity defect which is characteristic of bluff body wakes.

On the influence of viscosity and caustics on acoustic streaming in sessile droplets: an experimental and a numerical study with a cost-effective method

When an acoustic wave travels in a lossy medium such as a liquid, it progressively transfers its pseudo-momentum to the fluid, which results in a steady flow called acoustic streaming. This phenomenon involves a balance between sound attenuation and shear, such that the streaming flow does not vanish in the limit of vanishing viscosity. Hence, the effect of viscosity has long been ignored in acoustic streaming experiments. Here, we investigate the acoustic streaming in sessile droplets exposed to surface acoustic waves. According to experimental data, the flow structure and velocity magnitude are both strongly influenced by the fluid viscosity. We compute the sound wave propagation and hydrodynamic flow motion using a numerical method that reduces memory requirements via a spatial filtering of the acoustic streaming momentum source terms. These calculations agree qualitatively well with experiments and reveal how the acoustic field in the droplet, which is dominated by a few caustics, controls the flow pattern. We evidence that chaotic acoustic fields in droplets are dominated by a few caustics. It appears that the caustics drive the flow, which allows for qualitative prediction of the flow structure. Finally, we apply our numerical method to a broader span of fluids and frequencies. We show that the canonical case of the acoustic streaming in a hemispherical sessile droplet resting on a lithium niobate substrate only depends on two dimensionless numbers related to the surface and bulk wave attenuation. Even in such a baseline configuration, we observe and characterize four distinct flow regimes.

Research on the Stress and Material Flow with Single Particle—Simulations and Experiments

The scratching process of particle is a complex material removal process involving cutting, plowing, and rubbing. In this study, scratch experiments under different loads are performed on a multifunctional tester for material surface. Natural diamond and Fe-Cr-Ni stainless steel are chosen as indenter and workpiece material, respectively. The cutting depth and side flow height of scratch are measured using a white light interferometer. The finite element model is developed, and the numerical simulation of scratching is conducted using AdvantEdgeTM. The simulated forces and side flow height under different cutting depths correspond well with experimental results, validating the accuracy of the scratching simulation. The mises stress distribution of the particle is presented, with the maximum stress occurring inside the particle rather than on the surface. The pressure distribution of the particle is also given, and results show that the maximum pressure occurs on the contact surface of particle and workpiece. The material flow contour is presented, and material flow direction and velocity magnitude are analyzed.

An experimental and computational investigation of vortex formation in an unbaffled stirred tank

The present article focuses on the quantification of the depth of a depression (i.e. a vortex) formed when stirring liquids in an unbaffled stirred vessel. Based on several experiments, we show that while the vortex depth may be described very well by Nagata’s (1975) inviscid model for large Reynolds number (ReD=ND2ν≳104) this model does not apply for smaller Reynolds numbers. A number of researchers (e.g. Zlokarnik (1971), Rieger et al. (1979)) have addressed this difficulty by including Reynolds number in their correlations. However, those correlations produce unphysical estimates for ReD≲103 – a situation still of considerable industrial relevance. To this end, we have developed a new correlation based on 100 experiments where viscosity, impeller size, agitation speed, and impeller submergence were independently varied. The new correlation significantly extends the range of Reynolds numbers over which it can be applied (ReD∈(102,105)), and has the appropriate inviscid behavior, unlike the prior models. Using validated computer simulations in OpenFOAM, and additional experiments the correlation has been validated at various scales (0.046m to 0.92m tank diameters). The computational results also provide insights into the effect of fluid viscosity on the overall flow structure within the tank. In particular, the flow velocity magnitude rapidly decays away from the impeller for ReD≲103, and the flow is no longer dominated by tangential motion of the fluid. Consequently, under viscous conditions, the surface motion and vortexing diminish rapidly as impeller submergence is increased.

Separations and secondary structures due to unsteady flow in a curved pipe

Unsteady flows in highly curved geometries are of interest in many engineering applications and also in physiological flows. In this study, we use flow visualization and computational fluid dynamics to study unsteady flows in a highly curved tube ($\unicode[STIX]{x1D6FD}=0.3$) with square cross-section; here, $\unicode[STIX]{x1D6FD}$ is the ratio of the half edge length to the radius of curvature of the tube. To explore the combined effects of curvature and pulsatility, we use a single flow pulse of duration $T$ and peak area averaged axial velocity $U_{p(max)}$, which are independently varied to investigate a range of Dean and Womersley numbers. This range includes cases corresponding to flows in the ascending aorta. We observe radially inward moving secondary flows which have the structure of wall jets on the straight walls; their subsequent collision on the inner wall leads to a re-entrant radially outward moving jet. The wall jet arises due to an imbalance between the centrifugal force and the radial pressure gradient. During the deceleration phase, the low-axial-momentum fluid accumulated in the jet reverses direction and leads to flow separation near the inner wall. We use boundary layer equations to derive scales, which have not been reported earlier, for the secondary flow velocities, the wall shear stress components and the distance ($\hat{P}$) traversed by the secondary flow structures in the transverse plane. We show that $\hat{P}$ predicts the movement of vortical structures until collision. In the limit $\unicode[STIX]{x1D6FD}\rightarrow 0$, the Reynolds number based on this secondary flow velocity scale asymptotes to the secondary streaming Reynolds number proposed by Lyne (J. Fluid Mech., vol. 45 (01), 1971, pp. 13–31) in loosely curved pipes. The magnitude of the secondary flow velocity is high and ${\sim}40\,\%$ of $U_{p(max)}$ for physiological flow conditions. We show that the flow separation on the inner wall has origins in the secondary flow, which was reported in a few earlier studies, and is not due to the axial pressure gradient in the tube as proposed earlier. The wall shear stress components, hypothesized to be important in arterial mechanobiology, may be estimated using our scaling relations for geometries with different curvatures and varying pulsatilities.

Response of unconfined turbidity current to normal‐fault topography

AbstractTurbidity currents descending the slopes of deep‐water extensional basins or passive continental margins commonly encounter normal‐fault escarpments, but such large‐magnitude phenomena are hydraulically difficult to replicate at small scale in the laboratory. This study uses advanced computational fluid dynamics numerical simulations to monitor the response of large, natural‐scale unconfined turbidity currents (100 m thick and 2000 m wide at the inlet gate) to normal‐fault topography with a maximum relief of nearly 300 m. For comparative purposes, the turbidity current is first released on a non‐faulted pristine slope of 1·5° (simulation model 1). The expanding and waxing flow bypasses the slope without recognizable deposition within the visibility limit of 8 vol.% sand grain packing. Similar flow is then released towards the tip (model 2) and towards the centre (model 3) of a normal‐fault escarpment. In both of these latter models, the sand carried by flow tends to be entrapped in four distinct depozones: an upslope near‐gate zone of flow abrupt expansion and self‐regulation; a flow‐transverse zone at the fault footwall edge; a flow‐transverse zone at the immediate hangingwall; and a similar transverse zone near the crest of the hangingwall counter‐slope, where some of the deposited sand also tends to be reshuffled to the previous zone by a secondary reverse underflow. The near‐bottom reverse flow appears to be generated on a counter‐slope of 1·1°, increased to 2·0° by deposition. The Kelvin–Helmholtz interface instability plays an important role by causing three‐dimensional fluctuations in the flow velocity magnitude and sediment concentration. The thick deposits of large single‐surge flows may thus show hydraulic fluctuations resembling those widely ascribed to hyperpycnal flows. The study indicates further that the turbiditic slope fans formed on such fault topographies are likely to be patchy and hence may differ considerably from the existing slope‐fan conceptual models when it comes to the spatial prediction of main sand depozones.

Numerical simulation of mixing vanes on flow and heat transfer characteristics in 5 × 5 rod bundle

Single-phase heat transfer characteristics in a pressurised water reactor (PWR) fuel assembly are important. Many investigations have studied flow features in a 5 × 5 rod bundle with a specific mixing vane spacer grid. Three shapes and two arrangements of mixing vane are analysed to compare flow characteristics and heat transfer. No one-to-one correspondence exists between the block ratio and total pressure loss and the heat transfer for different mixing vanes shapes. The cross flow significantly affects the wall heat transfer coefficient of the rods. Cross flow in the channels for the two arrangements in the flow field differs greatly, and the cross flow is more obvious when the mixing vane adopts the second arrangement. Mixing-vane shape mainly affects the magnitude of the cross flow velocity - not the structure - and the Shape2 mixing vane induces maximum cross flow. These influences on cross flow result in a higher heat transfer with the second arrangement or with the second shape than with the first arrangement or the first- and third-shape mixing vanes.

A study of geometrical structure of packed beds using flow simulation with the immersed boundary method

In this work, a new method is proposed for calculation of one of the essentials geometrical parameters characterising a packed bed - tortuosity. The geometry of random packings of cylinders and rings (with various packing densities) is numerically generated with Discrete Element Method approach. For flow calculations in a highly complex geometry of a random packed bed, immersed boundary method is employed (with direct forcing variant). The obtained flow velocity field allows for calculation of tortuosity using two methods: by passive advection of massless particles and by comparison of the mean flow velocity magnitude with the mean streamwise velocity component. It is demonstrated that for the packings of low density these two methods are in a good agreement but may diverge for dense packings. Frequency distribution of tortuosity values for individual flow paths is also examined. The results show more frequent occurrence of low-tortuosity paths for coarse packings.

Trajectory-Diffusive Mechanism of Desilt Basin Operation

Within the framework of the generalized theory of turbulent diffusion, we consider the mean velocities, times, length of alternating transverse up-and-down motion of suspended particles in sediment exhibiting different settling velocities and fluid particles in calm uniform wide open flows. Experimental data obtained by various authors are used to find the maximum heights and lengths of particle saltation in the thin near-bottom region, as well as the magnitude of the dynamic flow velocity, which triggers the motion of particles on the bottom. From the combined trajectory description of particle motion in sediments of different settling velocities over the entire depth of an open flow, the trajectory limit settling velocity of suspended sediments deposited in a rectilinear desilt basin may be determined and, within the framework of relaxation models, the length of silting and erosion at the bottom may be found.