Variation Of Flow Velocity Research Articles

Performance investigation of a drag-based hydrokinetic turbine considering the effect of deflector, flow velocity, and blade shape

Hydrokinetic energy harnessing technologies are steadily acquiring the center stage of the modern renewable industry due to certain merits over the others. Significant research funding is being granted to institutions worldwide for optimizations and innovations in existing hydrokinetic devices. This numerical study focuses on one of the drag-based hydrokinetic turbines (HKTs) which has the potential to be a fitting choice for small-scale power conversion. A commercial solver in combination with the renormalized group (RNG) k-ε turbulence model is used to solve the unsteady Reynolds-Averaged Navier -Stokes (URANS) equations. The investigation highlights the role of the upstream deflector in exhibiting exceptional energy conversion efficiency by the HKT. Furthermore, the influence of flow velocity variations and differing blade profiles on the overall performance is also studied. In addition to analyzing the performance parameters, discussions on the flow behavior around the HKT blades are also presented. The results reveal that the use of deflector enhances the performance of the system by improving the efficiency up to 31%. Similarly, amplification of the incoming flow velocity has a positive impact on the torque generation and subsequently the power harnessing ability. From the various blade profiles simulated, the turbine with a rotor drum diameter (DR) of 0.25 extracted greater power output compared to the others including the conventional blade.

Flow Development in Radial Plane of Rotating Detonation Engine Integrated with Aerospike

In this study, axial and radial velocity components are measured downstream of a rotating detonation engine (RDE) integrated with an aerospike by using particle image velocimetry (PIV) at 100 kHz. The RDE is operated at high pressures obtained by restricting the RDE exit with a converging nozzle, which also directs the flow radially toward the aerospike. Reactants, methane fuel, and enriched air (67% oxygen and 33% nitrogen) are supplied from separate plenums at ambient temperature. PIV data are presented to investigate how pressure ratios within the RDE channel affect the flow evolution across the aerospike. The RDE is shown to operate stably and consistently in a single wave mode for all six test runs. The study highlights large temporal and spatial variations in both axial and radial flow velocities at the nozzle throat that persist downstream across the aerospike. Each point in the flowfield oscillates at the frequency recorded inside the RDE channel. Overall, the temporally and spatially varying aerospike flowfield is far from the ideal case of a uniform flow at its exit, and it points toward the need to condition the flow within the RDE channel to produce more uniform conditions at the nozzle throat.

Effects of gravel content on runoff and sediment yield on Lou soil engineering accumulation slopes under simulated rainfall conditions.

To investigate the effects of gravel content on runoff and sediment yield on Lou soil accumulation slopes, we conducted indoor simulation rainfall experiments and examined the characteristics of runoff and sediment yield on accumulation slopes with five gravel contents (10%, 20%, 30%, 40%, 50%) under four rainfall intensities (1.0, 1.5, 2.0, 2.5 mm·min-1), with a no gravels slope as control. The average runoff rate under different test conditions ranged from 2.18 to 13.07 L·min-1. The average runoff rate was the maximum under the gravel content of 10% (or 20%) and the minimum under the 50% gravel content. The average flow velocity ranged from 0.06 to 0.22 m·s-1. The variation of flow velocity was complex. The smaller the gravel content, the larger the range of variation and the coefficient of variation. The average flow velocity reached the maximum when the gravel content was 10%. The presence of gravel effectively inhibited the sediment yield, and the sediment reduction benefit reached 84.2%. The rainfall intensity had more influence on the average sediment yield rate than gravel content. Results of partial correlation analysis showed that gravel content was significantly negatively correlated with the ave-rage runoff rate, the average flow velocity, and the average sediment yield rate. The relationships between the ave-rage sediment yield and the average runoff rate, the average flow velocity, and their interaction were all extremely significant linear functions, with the strongest relationship between the average sediment yield and the average runoff rate. This study could provide references for the control of soil erosion and the establishment of erosion models for engineering accumulations in Lou soil areas.

Effect of Velocity and Type of Cooling Fluid on Peltier Heat Transfer for Car Cabin Cooling Applications

This research used the Peltier element as a car cabin cooler. This research aimed to compare the results of the lowest temperature produced by the Peltier element on the hot side. The design of this monitoring tool consists of LM35 as a temperature sensor and an electric velocity sensor to measure the velocity of the cooling fluid. Arduino Uno Microcontroller to control the system before being displayed to the LCD. The type of research used in this research is experimental research. In this study, variations in fluid flow velocity and type of cooling fluid were carried out. The fluid used is a mixture of water and water coolant with a ratio of 50%:50%. The results showed that the circulation of fluid cooling influences the temperature on the hot side of the Peltier. In cooling using water fluid, when the water pump rotates 4.5 liters/second, the temperature on the hot side of the Peltier is 36ᵒC. At the time of rotation of 13 liters/second, the temperature on the hot side of the Peltier is 32ᵒC. The difference between cooling using water fluid, water coolant, or a mixture of water and water coolant greatly affects the temperature produced on the cold side of the Peltier. In cooling using water, the lowest temperature produced reaches 8ᵒC. When the cooling using a fluid coolant, the lowest temperature reaches 6ᵒC. While cooling using a mixture of water and coolant, the lowest temperature reaches 3ᵒC. So it can be concluded that cooling using a mixture of water and water coolant is very effective compared to other fluid coolers.

Reach hydromorphology: a crucial environmental variable for the occurrence of riverine macrophytes

Management measures targeting riverine macrophyte species often address dissolved nitrogen and phosphorus compounds. With recent reductions of nutrient pollution, effects of other variables have become more apparent. This study aims to shed light on the hierarchy of variables determining riverine macrophyte distribution, covering both surface water nutrients and a range of other variables, in a Central European landscape. We used a dataset of 1,371 monitoring samples to predict the presence and absence of 30 common macrophyte species with multiple random forest models. Besides surface water chemical variables (P-PO4, TN and pH), five reach hydromorphological variables (substrate, flow velocity, shading, width and depth) and a variable related to river size (distance from the river source) were use as predictors. The most important variables for the prediction of the species’ presence and absence were substrate, distance from the river source and flow velocity. Additionally, P-PO4 and shade were also important, whilst TN, pH, width and depth played only a minor role. River hydromorphology was more important than surface water chemistry for the occurrences of individual riverine macrophyte species, in particular under less extreme eutrophic conditions. Species occurrences were related to multiple interacting variables, amongst which hydromorphology often prevailed. Presence/absence of species and composition of assemblages cannot be attributed to surface water nutrients alone, even when considering river typologies. Therefore, the results support the conjecture that a broader approach considering a range of stressors is necessary to design restoration measures for management and enhancement of macrophyte diversity.

Mechanistic model of combined pressure drop and heat transfer for the entire growth stage of an elongated bubble in a rectangular microchannel

A one-dimensional flow-boiling model for the slug-flow regime is formulated to describe the pressure drop and heat transfer mechanism in a microchannel of rectangular cross-section. The pressure drop model considers three stages of bubble growth namely: (i) partial confinement, (ii) full confinement and (iii) vapour venting. The heat transfer coefficient at any particular location is obtained by assuming the periodic passage of four zones: (i) liquid slug zone, (ii) elongated bubble zone, (iii) partially dryout zone, and (iv) fully dryout zone. The model is evaluated using constant fluid properties, to study the parametric variation of channel pressure drop and heat transfer coefficient. The effects of variation in channel dimension, flow velocity, heat flux and properties of working fluid on pressure drop and heat transfer coefficient have been studied using the model. The model is capable of simulating all the transport processes for a single bubble from its inception till it leaves the microchannel and thereby it can estimate the pressure drop in the channel along with the heat transfer coefficient i.e. spatially averaged over the channel length and at any location from channel upstream to the downstream end.

Stall flutter prediction based on multi-layer GRU neural network

The modeling of dynamic stall aerodynamics is essential to stall flutter, due to the flow separation in a large-amplitude pitching oscillation process. A newly neural network based Reduced Order Model (ROM) framework for predicting the aerodynamic forces of an airfoil undergoing large-amplitude pitching oscillation at various velocities is presented in this work. First, the dynamic stall aerodynamics is calculated by solving RANS equations and the transitional SST-γ model. Afterwards, the stall flutter bifurcation behavior is calculated by the above CFD solver coupled with structural dynamic equation. The critical flutter speed and limit-cycle oscillation amplitudes are consistent with those obtained by experiments. A newly multi-layer Gated Recurrent Unit (GRU) neural network based ROM is constructed to accelerate the calculation of aerodynamic forces. The training and validation process are carried out upon the unsteady aerodynamic data obtained by the proposed CFD method. The well-trained ROM is then coupled with the structure equation at a specific velocity, the Limit-Cycle Oscillation (LCO) of stall flutter under this flow condition is predicted precisely and more quickly. In order to predict both the critical flutter velocity and LCO amplitudes after bifurcation at different velocities, a new ROM with GRU neural network considering the variation of flow velocities is developed. The stall flutter results predicted by ROM agree well with the CFD ones at different velocities. Finally, a brief sensitivity analysis of two structural parameters of ROM is carried out. It infers the potential of the presented modeling method to depict the nonlinearity of dynamic stall and stall flutter phenomenon.

Analytical model for predicting the lateral profiles of velocities through a partially vegetated channel

In an open channel, an emergent canopy of vegetation enhances local resistance, producing a complicated velocity distribution within and around the canopy. Laboratory experiments were performed to understand the flow velocity variations in a partially vegetated channel, revealing both streamwise and lateral velocity variations as the flow entered the canopy. An analytical model was proposed to predict the lateral velocity profiles across the vegetated region and bare channel in both the flow adjustment region and the fully developed flow region. The flow velocity variations in the streamwise and lateral directions were parameterized and included in the new proposed model, allowing the model to capture both the streamwise and the lateral velocity variations. Twenty sets of experimental data from our experiments and data from published studies were used to verify the new model. The predicted velocity profiles exhibited good agreement with the measurements under a wide range of vegetation and flow conditions, suggesting that the proposed model is capable of accurately predicting the velocity profiles in a partially vegetated channel. Finally, the proposed model was applied to evaluate the critical frontal area per canopy volume at which Kelvin–Helmholtz vortices form along the emergent canopy side edge. With the same spatially averaged velocity, the critical frontal area exhibited no dependence on stem diameter.

Investigation of Non-Newtonian Characteristics of Water Flow in Micro-/Nanochannels and Tight Reservoirs

The characteristic scale of pore flow in tight reservoirs is generally in the range of 0.1 μm to 1 μm, which shows the obvious micro- and nanoscale effect. The traditional oil and gas seepage theory cannot accurately describe the flow law of liquid in the micro- and nanopores. The determination of seepage characteristics is crucial to the development, layout, and prediction of tight oil. Therefore, a non-Newtonian fluid model is established to discuss the flow characteristics of confined liquid in the heterogeneous pores of microtubules and reveal the nonlinear seepage law of water in micro- and nanochannels and tight reservoirs. Based on the characteristics of non-Newtonian fluid of confined fluid in micro- and nanospace, the flow model of non-Newtonian fluid under the action of shear stress was deduced. The flow velocity variation of liquid in micro- and nanochannel and dense core was analyzed, and the flow rate of water was less than that predicted by macro theory. According to the flow experiment of water in micro- and nanochannels, the flow model of power-law non-Newtonian fluid was verified. At the same time, through the flow experiment of water in the dense rock core, the non-Newtonian model was used for nonlinear fitting, and the non-Newtonian power-law parameters and average pore radius were obtained, which verified the effectiveness of the non-Newtonian flow model.

Effect Evaluation of Norepinephrine on Cardiac Function in Patients with Sepsis by Cardiac Ultrasound Imaging.

In order to investigate the therapeutic effect of norepinephrine on patients with sepsis and the effect of echocardiography on the diagnosis of cardiac function in patients with sepsis, 86 patients with sepsis were selected as research objects and randomly divided into two groups. Patients in the control group (N = 43 cases) received conventional treatment (1~15 μg/kg∗min dopamine), and those in the experimental group (N = 43 cases) received conventional treatment+norepinephrine therapy (0.05~0.5 μg∗kg−1/min). The clinical efficacy, cardiac ultrasonography results, and hemodynamic indexes of patients between the two groups were analyzed and compared. The results showed that the total effective rate of treatment in the experimental group (97.7%) was significantly higher than that in the control group (81.4%) (P < 0.05). The maximum, minimum, and average values of mitral valve E peak flow velocity (VEpeak) and left ventricular outflow tract peak flow velocity (Vpeak), respiratory variability of mitral valve E peak flow velocity (ΔVEpeak), and respiratory variability of peak flow velocity (ΔVpeak) were all significantly greater than those of the control group (P < 0.05). The area under the receiver operating characteristic curve (AUC) of ΔVEpeak and ΔVpeak for predicting positive volume response in patients with sepsis was 0.934 and 0.913, respectively; the sensitivity was 0.828 and 0.827; the specificity was 0.936 and 0.893; and the Youden indices were 0.765 and 0.712, respectively. In short, norepinephrine had a high total response rate in patients with sepsis, and echocardiography can well evaluate the effect of norepinephrine on cardiac function in patients with sepsis, which is worthy of further promotion.

Studi Eksperimen Kinerja Penukar Kalor Kompak Sebagai Pemanas Tambahan di Rumah Pengering Hibrid

The process of drying a hybrid system that uses a combination of solar energy and biomass contains some useful heat in the chimney of the biomass stove. This heat waste has a high enough temperature so that with the help of a compact heat exchanger it can be used as an additional heater. The purpose of this study was to analyze the performance of a cross-flow type discrete flat plate-finned tube compact heat exchanger with an inline tube arrangement which is used as an additional heating device in the hybrid dryer housing. The test was carried out at 10.00-15.00 for three days of testing with variations in air flow velocity of 1.3 m/s, 1.6 m/s and 1.8 m/s while the velocity of water flow in the pipe was considered constant with 0.000168 m/s. s and the air flow velocity in the exhaust fan is kept constant at 1 m/s. The results of this study indicate that the overall heat transfer coefficient is strongly influenced by the effectiveness of the heat exchanger, and with the increase in the effectiveness of the heat exchanger, the heat transfer coefficient will also increase. The highest overall heat transfer coefficient was obtained on the second day, namely 99.263 W/m2.oC. The total heat transfer rate is influenced by the effectiveness of the heat exchanger but at a certain value both values ​​tend to be stable due to the limited dimensions of the heat exchanger. NTU is very influential on the effectiveness of the exchanger, and in this case the value of NTU ranges from 0.6-0.8 while the effectiveness of the heat exchanger ranges from 46%-56%

The implementation of transcranial Doppler ultrasonography for preclinical study of migraine.

Transcranial Doppler ultrasonography is used to study intracranial blood flow changes associated with migraine in humans, but whether this method is helpful in preclinical settings is yet unknown. To identify changes in rat intracranial blood flow specific to trigeminovascular activation-a key process in migraine pathophysiology-we measured Doppler indices in the middle cerebral artery and basilar artery before, during, and after dural or somatosensory electrical stimulation. Hemodynamic changes specific to dural stimulation were tested further in separate experiments. After baseline recordings, the animals received cumulative infusions of valproate (100 mg/kg, trice), sumatriptan (0.3, 1, and 3mg/kg), or saline, and dural stimulation with measurement of Doppler indices was repeated every 10 min for 1 h. Several parameters of blood flow in the rat middle cerebral artery underwent alterations specific to trigeminovascular activation. These changes, however, were insensitive to valproate and sumatriptan and diminished over time. These findings question the reliability of blood flow velocity variations in large intracranial vessels as biological markers of migraine-related processes and do not support the idea of using transcranial Doppler ultrasonography for preclinical screening of antimigraine treatments, at least in the model of acute trigeminovascular activation in rats.

Numerical modeling of atmospheric pollution in the approaches of random selection of discrete dusting sites and interval distribution of dust size

The results of numerical simulation of atmospheric pollution in Apatity are presented with variations in the dusting area of discrete spatially spaced areas selected randomly and the wind flow velocity. CFD modeling in the volumetric formulation was performed using the COMSOL program. To calculate the aerodynamic characteristics, an incompressible fluid approximation was used using the standard ( k -ε) turbulence model. The process of fine dust propagation is modeled by numerical solution of the convective-diffusion impurity transfer equation taking into account the deposition rate. Numerical experiments (with a total number of more than 1,400) were carried out with a variation of the wind flow velocity from 5 to 23 m/s and a dusting area from 2 to 10 ha with a random selection of 20 discrete sites. Dynamic velocity distributions for specific areas of dusting, interval and total spatial distributions of dust pollution (dust particles with a diameter from 0 to 70 microns in increments of 10 microns) are obtained. The peculiarities of the influence on the levels of atmospheric pollution of specific areas of Apatity depending on the location of dusty areas on the surface of the beach of the tailings dump are noted. The calculated levels of atmospheric pollution in the center of Apatity averaged by the number of combinations of dusting sites are analyzed and generalized to functional dependencies. The calculated dependences of the dust concentration on the dusting area at a fixed wind speed are described by linear functions. The dependence of the dust concentration on the wind flow velocity at a fixed dusting area can be approximated by a power function. The generalized functional dependence makes it possible to predict the dust concentration in Apatity depending on the dusting area of randomly selected discrete areas on the surface of the tailings dump and the wind flow velocity. The obtained dependence permits to make a forecast of the critical dusting area at which the level of atmospheric pollution reaches the maximum permissible concentrations, depending on the speed of the wind flow.

Numerical Investigation of the Effect of Rigid Vegetation at an Inclined Bank, on Streamflow Hydrodynamics

Abstract This study is a computational analysis of hydrodynamic alterations of flow such as secondary current, turbulent kinetic energy, and shear stress, in an open channel with an increased vegetation density at an inclined bank. Two arrangements of rigid vegetation at an inclined bank, linear and staggered, are investigated for five different vegetation density. The computational analyses are performed under constant flow and stable bed conditions. The variations of stream wise flow velocity, turbulent kinetic energy, and Reynolds stress along the main channel are evaluated and presented for each vegetation density. The results illustrated the impacts of vegetation density on the entire channel flow characteristics. These results are further analyzed based on average bed shear stress calculations. The main outcome of the study demonstrated that combined effect of inclined bank and effect of partly obstructed flow significantly generates Kelvin-Helmholtz type instability due to the presence of inflection point at different location along a vegetation cover. The calculated Reynolds stresses are higher at the main channel bed near the vertical bank, but shift to midflow depths near the boundary between the main channel and inclined bank. The turbulence kinetic energy profiles in the main channel and at the inclined bank exhibited results that were similar and parallel to the simulated stream wise velocities and Reynolds stresses. Furthermore, it is found that the ratio between bed shear stress and turbulent kinetic energy is almost 0.3 as the depth approaches the channel bed.

Cross-flow vortex-induced vibration of a flexible fluid-conveying riser undergoing external oscillatory flow

Cross-flow (CF) vortex-induced vibration (VIV) of a flexible riser considering both internal flow and external oscillatory flow is numerically investigated with consideration of combining the structural model with semi-empirical hydrodynamic force model by using Finite Element Method. The accuracy of the applied model is firstly examined by comparing the numerical results with the experimental data, which proves that the model can reproduce typical characteristics of CF VIV of a flexible riser undergoing external oscillatory flow. Then CF VIV of a flexible fluid-conveying riser subjected to external oscillatory flow is studied while the non-dimensional internal flow velocity and density ratio between internal and external flows are changed. The results show that regardless of the non-dimensional internal flow velocity and density ratio, typical VIV features of a flexible riser, such as intermittent VIV, amplitude modulation, hysteresis, mode and frequency transitions as well as standing and travelling wave responses, can be captured with variation of external oscillatory flow velocity. Moreover, VIV developing process, including building-up, lock-in and dying-out, can be detected for CF VIV. With the increase of the non-dimensional internal flow velocity and density ratio, high mode response can be effortlessly triggered for CF VIV, which is accompanied with occurrence of new vibrating frequencies. In addition, the vibrating frequency of CF VIV decreases while the non-dimensional internal flow velocity and density ratio are increased.

Combustion Characteristics of Methane-Air Mixtures in Millimeter-Scale Systems With a Cavity Structure: An Experimental and Numerical Study

The management of internal features of a cavity structure for channels offers the possibility of inherently effective operation within the flammable limits of a combustible fluid stream while preserving high stability for the flame. However, the precise mechanism by which the cavity method generally provides increased flame stability for millimeter-scale systems remains unclear. The combustion characteristics of methane-air mixtures in millimeter-scale systems with a cavity structure were investigated experimentally and numerically to gain a greater understanding of the mechanisms of flame stabilization and to gain new insights into the characteristics of combustion within spaces with extremely small dimensions. The quenching distance was determined both experimentally and numerically. Stable temperature profiles were obtained from thermographic measurements using infrared radiation. The measurements were compared with the model predictions. Subsequent model calculations demonstrate the effects of variations in wall thermal conductivity, heat losses, flow velocity, equivalence ratio, and channel dimensions. Design recommendations were made. The experimental and numerical results indicated that the quenching distance is slightly larger than commonly believed. The cavity structure has little effect on the quenching distance, but can improve the efficiency and performance of the systems considerably. The cavity structure can effectively extend flammability limits, with an increase of about 18% in the operating range defined by the equivalence ratio of the mixture. The length scale of the systems plays a vital role in stabilizing the flame. The thermal conductivity of the solid material is vital in determining the efficiency and performance of the systems. The design with anisotropic thermal conductivity has significant performance advantages. The flow velocity of the fluid and the equivalence ratio of the mixture are important factors affecting the efficiency and performance of the systems.

Influence of Flow Velocity Variability on Pipeline Stability Boundaries

Influence of Flow Velocity Variability on Pipeline Stability Boundaries

Utility of Transfontanelle Ultrasound in Predicting the Fluid Responsiveness in Children After Repair of Congenital Heart Diseases: A Prospective Observational Study

Postoperative fluid management in children undergoing cardiac surgery requires a balanced optimization. The blood flow velocity variation in the internal carotid artery (ΔICA) measured through transfontanelle ultrasound has been shown to predict fluid responsiveness during cardiac surgery. It may provide an excellent window to study fluid responsiveness in infants during the postoperative period when the intensivist is faced with the challenges of poor echocardiographic window. The authors aimed to observe the correlation between ΔICA measured on transfontanelle ultrasound with the respiratory variability of peak aortic blood flow velocity (ΔVpeak) on transthoracic echocardiography as a marker of fluid responsiveness in infants on mechanical ventilation during the postoperative period after cardiac surgery. A prospective observational study. The postcardiac surgery intensive care unit (ICU) of a tertiary care hospital. Thirty infants undergoing congenital cardiac surgery. A fluid bolus of 10 mL/kg administered over 10 minutes at 1 and 6 hours after ICU admission. Patients were categorized into fluid responders and nonresponders based on >15% increase in the indexed stroke volume. A total of 50 fluid boluses were administered in 30 patients. Among these, 22 (73.33%) were responders and 8 (26.67%) were nonresponders. There was moderate correlation between ΔICA and peak aortic blood flow velocity variation (ΔVpeak) (r=0.59, p ≤ 0.001). The ΔVpeak >14.74% had 68% sensitivity and 75% specificity to predict fluid responsiveness (area under the receiver operating characteristic [AUROC], 0.749; p=0.001; positive likelihood ratio, 2.71; negative likelihood ratio, 0.43). The ΔICA >9.85% could predict fluid responsiveness in infants (AUROC, 0.728; p=0.003; 75% sensitivity; 60% specificity; positive likelihood ratio, 1.85; negative likelihood ratio, 0.42). Among children younger than 6 months, ΔICA >9.85% was a better predictor of fluid responsiveness (AUROC, 0.889; p=0.009) than ΔVpeak >15% (AUROC, 0.778; p=0.061). The ICA variability >9.85% measured via transfontanelle ultrasound is a good predictor of fluid responsiveness in infants, especially those younger than 6 months on mechanical ventilation after cardiac surgery.

Flow Velocity Variations and Surface Change of the Destabilised Plator Rock Glacier (Central Italian Alps) from Aerial Surveys

Flow velocities were measured on the Plator rock glacier in the Central Italian Alps using a correlation image analysis algorithm on orthophotos acquired by drones between the years 2016 and 2020. The spatial patterns of surface creep were then compared to the Bulk Creep Factor (BCF) spatial variability to interpret the rock glacier dynamics as a function of material properties and geometry. The rock glacier showed different creep rates in the rooting zone (0.40–0.90 m/y) and in the frontal zone (&gt;4.0 m/y). Close to the rock glacier front, the BCF assumed the highest values, reaching values typical of rock glaciers experiencing destabilisation. Conversely, in the rooting zone the small rates corresponded to lowest BCFs, about five times smaller than in the frontal zone. The Plator rock glacier revealed a substantial advancement from 1981 to 2020 and distinct geomorphological features typical of rock glaciers exhibiting destabilising processes. Given the fast-moving phase, the advancement of both the front line and the front toe of the rock glacier, and the contrasting spatial distribution in the BCFs, the Plator could be considered a destabilised rock glacier.

A hybrid FEM-DNN-based vortex-induced Vibration Prediction Method for Flexible Pipes under oscillatory flow in the time domain

In this paper, a hybrid FEM-DNN-based vortex-induced vibration (VIV) prediction method for flexible pipes under an oscillatory flow in the time domain is proposed. In this method, a vortex-induced force coefficient model is regressed by a deep neural network (DNN) from experimental data. The model takes into account the effects of flow velocity variation, VIV responses and their coupling features on vortex-induced forces. Then, it is combined with finite element method (FEM) to predict the VIV responses of flexible pipes in time domain. In addition, a phase modulation model is developed to ensure that synchronization between forces and responses can be achieved. The proposed prediction method is used to predict the VIV responses of the flexible pipe used in DNN regression training under oscillatory flows. Comparisons between the predicted results and the experimental results are conducted to verify the feasibility and accuracy of the proposed method. Then, the generalizability of the proposed method is further verified via comparisons between the predicted VIV results and the experimental results of another flexible pipe whose structural parameters are different from the DNN training pipe.