基于FLOW3D的集成式水下基盘泥沙冲淤三维数值模拟

泥面下集成式水下基盘是为开采渤海通航区等海域油气资源而提出的新型基盘,其基坑周围局部冲淤是工程实践关注的问题之一。基于不可压缩粘性流体运动的Navier-Stokes方程建立泥面下集成式水下基盘基坑周围三维水动力数学模型,对不同粒径和不同流速情况下的局部冲淤进行了模拟。结果表明:泥沙粒径为0.005 mm时,由于泥沙较难起动,基坑附近局部冲淤较小。粒径分别为0.05 mm和0.1 mm时,在典型流速作用下,基盘附近可分别形成1 m左右和4 m左右的淤积。

Depth-Guided Vision Transformer With Normalizing Flows for Monocular 3D Object Detection

Monocular 3D object detection is challenging due to the lack of accurate depth information.Some methods estimate the pixel-wise depth maps from off-the-shelf depth estimators and then use them as an additional input to augment the RGB images.Depth-based methods attempt to convert estimated depth maps to pseudo-LiDAR and then use LiDAR-based object detectors or focus on the perspective of image and depth fusion learning.However,they demonstrate limited performance and efficiency as a result of depth inaccuracy and complex fusion mode with convolutions.Different from these approaches,our proposed depth-guided vision transformer with a normalizing flows(NF-DVT)network uses normalizing flows to build priors in depth maps to achieve more accurate depth information.Then we develop a novel Swin-Transformer-based backbone with a fusion module to process RGB image patches and depth map patches with two separate branches and fuse them using cross-attention to exchange information with each other.Furthermore,with the help of pixel-wise relative depth values in depth maps,we develop new relative position embeddings in the cross-attention mechanism to capture more accurate sequence ordering of input tokens.Our method is the first Swin-Transformer-based backbone architecture for monocular 3D object detection.The experimental results on the KITTI and the challenging Waymo Open datasets show the effectiveness of our proposed method and superior performance over previous counterparts.

Identifying the enhancement mechanism of Al/MoO_(3) reactive multilayered films on the ignition ability of semiconductor bridge using a one-dimensional gas-solid two-phase flow model

Energetic Semiconductor bridge(ESCB)based on reactive multilayered films(RMFs)has a promising application in the miniature and intelligence of initiator and pyrotechnics device.Understanding the ignition enhancement mechanism of RMFs on semiconductor bridge(SCB)during the ignition process is crucial for the engineering and practical application of advanced initiator and pyrotechnics devices.In this study,a one-dimensional(1D)gas-solid two-phase flow ignition model was established to study the ignition process of ESCB to charge particles based on the reactivity of Al/MoO_(3) RMFs.In order to fully consider the coupled exothermic between the RMFs and the SCB plasma during the ignition process,the heat release of chemical reaction in RMFs was used as an internal heat source in this model.It is found that the exothermal reaction in RMFs improved the ignition performance of SCB.In the process of plasma rapid condensation with heat release,the product of RMFs enhanced the heat transfer process between the gas phase and the solid charge particle,which accelerated the expansion of hot plasma,and heated the solid charge particle as well as gas phase region with low temperature.In addition,it made up for pressure loss in the gas phase.During the plasma dissipation process,the exothermal chemical reaction in RMFs acted as the main heating source to heat the charge particle,making the surface temperature of the charge particle,gas pressure,and gas temperature rise continuously.This result may yield significant advantages in providing a universal ignition model for miniaturized ignition devices.

基于3dmax Particle Flow系统的矿的虚拟效果实现

以煤为矿的代表,在对煤的视觉特性进行分析的基础上,基于3dmax Particle Flow系统建立了采掘系统中采煤机和提升运输系统中的带式输送机工作过程中煤的模型,采用3dmax自身的渲染器渲染出了该过程的动画,该方法可用于简便真实的展示煤等矿的效果及相关机械的工作原理。

基于Flow3D软件对激光熔覆工艺过程的仿真研究

为了更好的了解工艺参数对激光熔覆过程的影响,本研究采用高斯面热源模型,通过Flow3D软件对激光与氮化硼复合粉末涂层的相互作用过程中温度场的分布以及涂层的演变过程进行了数值仿真模拟,结果表明当激光功率P=660W、扫描速度V=0.14m/s、光斑直径D=12μm时,单道熔覆层的成形效果最好。并根据最佳单道熔覆参数,以理论计算的搭接率设为模拟中的激光扫描间距进行双道搭接实验,得到最佳激光扫描间距为d=30μm,此时成形效果最佳,且无明显搭接痕迹。本研究探讨了不同工艺参数对熔覆层的影响,可为后续激光加工方法与技术的发展提供理论支撑。

3D topographic correction of the BSR heat flow and detection of focused fluid flow

The bottom-simulating reflector（BSR） is a seismic indicator of the bottom of a gas hydrate stability zone. Its depth can be used to calculate the seafloor surface heat flow. The calculated BSR heat flow variations include disturbances from two important factors：（1） seafloor topography, which focuses the heat flow over regions of concave topography and defocuses it over regions of convex topography, and（2） the focused warm fluid flow within the accretionary prism coming from depths deeper than BSR. The focused fluid flow can be detected if the contribution of the topography to the BSR heat flow is removed. However, the analytical equation cannot solve the topographic effect at complex seafloor regions. We prove that 3D finite element method can model the topographic effect on the regional background heat flow with high accuracy, which can then be used to correct the topographic effect and obtain the BSR heat flow under the condition of perfectly flat topography. By comparing the corrected BSR heat flow with the regional background heat flow, focused fluid flow regions can be detected that are originally too small and cannot be detected using present-day equipment. This method was successfully applied to the midslope region of northern Cascadia subducting margin. The results suggest that the Cucumber Ridge and its neighboring area are positive heat flow anomalies, about 10%–20% higher than the background heat flow after 3D topographic correction. Moreover, the seismic imaging associated the positive heat flow anomaly areas with seabed fracture–cavity systems. This suggests flow of warm gas-carrying fluids along these high-permeability pathways, which could result in higher gas hydrate concentrations.

浅谈3ds Max中Thinking Particles和Particle Flow的区别

Thinking Particles和Particle Flow是3ds Max中两大粒子系统,是动画师制作动画特效的两大利器,本文分别介绍了Thinking Particles和Particle Flow两个粒子系统的优缺点,并且从两个不同的方面讲述了两者的区别。

3D FEM simulation of flow velocity field for 5052 aluminum alloy multi-row sprocket in cold semi-precision forging process

Based on the design of the multi-row sprocket with a new tooth profile,a cold semi-precision forging process for manufacturing 5052 aluminum alloy multi-row sprocket was presented.Through simulating the forging process of 5052 aluminum alloy sprocket billet with 3D rigid-viscoplastic FEM,both the distributions of flow velocity field in axial(U_Z),radial(U_R) and circumferential(U_θ) directions and the curves of velocity component in different deformation regions were respectively obtained.By comparison and analysis of the velocity varying curves,the velocity component relation conditions for filling the die cavity were clarified.It shows that when the die cavity is almost fully filled,the circumferential velocity U_θ increases sharply,implying that U_θplays a key role in fully filling the die cavity.

基于FLOW3D模型浅析河道断面形状对河道水力特性的影响

由于自然地理形态各异,研究不同的河道断面形状,有利于认识了解整体河道的水力特性。该文基于FLOW3D模型,实现对5种河道断面形状的数值仿真计算结果的简要分析。通过对断面横、纵向流速的观测得出结论,复式梯形断面可作为最佳河道断面进行研究,曲线断面对河道水力特性的不利影响较为突出。

Numerical simulation of a combined oxidation ditch flow using 3D k-ε turbulence model

The standard three dimensional（3D） k-ε turbulence model was applied to simulate the flow field of a small scale combined oxidation ditch. The moving mesh approach was used to model the rotor of the ditch. Comparison of the computed and the measured data is acceptable. A vertical reverse flow zone in the ditch was found, and it played a very important role in the ditch flow behavior. The flow pattern in the ditch is discussed in detail, and approaches are suggested to improve the hydrodynamic performance in the ditch.

Prediction of flow stress of Ti-15-3 alloy with artificial neural network

Hot compression experiments were conducted on Ti 15 3 alloy specimens using Gleeble 1500 Thermal Simulator.These tests were focused to obtain the flow stress data under various conditions of strain,strain rate and temperature. On the basis of these data, the predicting model for the nonlinear relation between flow stress and deformation strain,strain rate and temperature for Ti 15 3 alloy was developed with a back propagation artificial neural network method. Results show that the neural network can reproduce the flow stress in the sampled data and predict the nonsampled data well. Thus the neural network method has been verified to be used to tackle hot deformation problems of Ti 15 3 alloy. [

Formaldehyde degradation by UV/TiO_2/O_3 process using continuous flow mode

The degradation of formaldehyde gas was studied using UV/TiO2/O3 process under the condition of continuous flow mode. The effects of humidity, initial formaldehyde concentration, residence time and ozone adding amount on degradation of formaldehyde gas were investigated. The experimental results indicated that the combination of ozonation with photocatalytic oxidation on the degradation of formaldehyde showed a synergetic action, e.g,, it could considerably increase decomposing of formaldehyde. The degradation efficiency of formaldehyde was between 73.6% and 79.4% while the initial concentration in the range of 1.84--24 mg/m^3 by O3/TiO2flJV process. The optimal humidity was about 50% in UV/TiO2/O3 processs and degradation of formaldehyde increases from 39.0% to 94.1% when the ozone content increased from 0 to 141 mg/m^3. Furthermore, the kinetics of formaldehyde degradation reaction could be described by Langmuir-Hinshelwood model. The rate constant k of 46.72 mg/（m^3.min） and Langmuir adsorption coefficient K of 0.0268 m^3/mg were obtained.

KHCO_3 activated carbon microsphere as excellent electrocatalyst for VO^(2+)/VO_2^+ redox couple for vanadium redox flow battery

In this paper,carbon microsphere prepared by hydrothermal treatment was activated by KHCO_3 at high temperature,and employed as the catalyst for VO^(2+)/VO_2^+redox reaction for vanadium redox flow battery(VRFB).Carbon microsphere can be etched by KHCO_3 due to the reaction between the pyrolysis products of KHCO_3 and carbon atoms.Moreover,KHCO_3 activation can bring many oxygen functional groups on carbon microsphere,further improving the wettability of catalyst and increasing the active sites.The electrocatalytic properties of carbon microsphere from hydrothermal treatment are improved by high temperature carbonization,and can further be enhanced by KHCO_3 activation.Among carbon microsphere samples,the VO^(2+)/VO_2^+redox reaction exhibits the highest electrochemical kinetics on KHCO_3 activated sample.The cell using KHCO_3 activated carbon microsphere as the positive catalyst demonstrates higher energy efficiency and larger discharge capacity,especially at high current density.The results reveal that KHCO_3 activated carbon microsphere is an efficient,low-cost carbon-based catalyst for VO^(2+)/VO_2^+redox reaction for VRFB system.

基于FLOW3D的梅溪洪濑段桥梁雍水三维数值模拟

为探究桥梁雍水与桥洞堵塞对洪泛区淹没情况的贡献,以山区河道梅溪洪濑段上的8座桥梁为例,借助FLOW3D模型构建精细化三维河道与桥梁模型。模型经过验证,模拟值的绝对误差平均值小于0.05 m,Nash系数大于0.77,表明模拟结果良好。分别计算各桥不同重现期下的雍水值,模拟桥洞堵塞程度的影响。结果表明:从整体来看,上游桥梁雍水值大部分大于下游桥梁点位;七号桥的雍水影响最大,在20 a、50 a和100 a重现期,对桥前洪泛区最大淹没水深的贡献比分别达到15.1%、18.5%与22.7%;桥孔堵塞程度增加的比例与桥前水位增量基本呈线性关系;相对于50 a无堵塞的情况,七号桥堵塞20%对桥前洪泛区最大淹没水深的贡献比又增加了21%,桥前平均水位甚至大于100 a无堵塞的洪水水位。本研究可以为梅溪洪濑段实际桥梁安全防护与河道沿岸洪泛区防洪减灾提供参考。

基于Flow 3D的海上风电单桩基础冲刷防护数值模拟研究

基于江苏竹根沙海上风电场项目典型海域水文地质资料,采用Flow 3D数值模拟方法,建立单桩基础局部冲刷数值模拟,分析不同尺寸圆形防护板对单桩基础局部冲刷保护效果的影响规律,得到了以下结论:无防护板时,单桩基础冲刷稳定阶段对应的最大冲刷深度为1.099 m;设置直径为36 m的圆形防冲刷板后,水流流速在防护板与泥面之间的小间隙内快速减缓,桩前出现堆积体,此时最大冲刷深度仅为无防护板时的11.8%左右;直径超过30 m的防护板都能显著限制单桩基础周围的局部冲刷程度,最大冲刷深度都在0.127 m左右。直径为36 m时,防护板所对应的最大冲刷深度最大,为0.13 m,但变化不大,故在实际工程中,可选择较小尺寸的圆形防护板,亦可达到相类似的效果。

A CFD Based Investigation of the Unsteady Hydrodynamic Coefficients of 3-D Fins in Viscous Flow

The motion of the fins and control surfaces of underwater vehicles in a fluid is an interesting and challenging research subject.Typically the effect of fin oscillations on the fluid flow around such a body is highly unsteady, generating vortices and requiring detailed analysis of fluid-structure interactions.An understanding of the complexities of such flows is of interest to engineers developing vehicles capable of high dynamic performance in their propulsion and maneuvering.In the present study, a CFD based RANS simulation of a 3-D fin body moving in a viscous fluid was developed.It investigated hydrodynamic performance by evaluating the hydrodynamic coefficients (lift, drag and moment) at two different oscillating frequencies.A parametric analysis of the factors that affect the hydrodynamic performance of the fin body was done, along with a comparison of results from experiments.The results of the simulation were found in close agreement with experimental results and this validated the simulation as an effective tool for evaluation of the unsteady hydrodynamic coefficients of 3-D fins.This work can be further be used for analysis of the stability and maneuverability of fin actuated underwater vehicles.

3D Particle Image Velocimetry Test of Inner Flow in a Double Blade Pump Impeller

The double blade pump is widely used in sewage treatment industry,however,the research on the internal flow characteristics of the double blade pump with particle image velocimetry（PIV） technology is very little at present.To reveal inner flow characteristics in double blade pump impeller under off-design and design conditions,inner flows in a double blade pump impeller,whose specific speed is 111,are measured under the five off-design conditions and design condition by using 3D PIV test technology.In order to ensure the accuracy of the 3D PIV test,the external trigger synchronization system which makes use of fiber optic and equivalent calibration method are applied.The 3D PIV relative velocity synthesis procedure is compiled by using Visual C＋＋ 2005.Then absolute velocity distribution and relative velocity distribution in the double blade pump impeller are obtained.Test results show that vortex exists in each condition,but the location,size and velocity of vortex core are different.Average absolute velocity value of impeller outlet increases at first,then decreases,and then increases again with increase of flow rate.Again average relative velocity values under 0.4,0.8,and 1.2 design condition are higher than that under 1.0 design condition,while under 0.6 and 1.4 design condition it is lower.Under low flow rate conditions,radial vectors of absolute velocities at impeller outlet and blade inlet near the pump shaft decrease with increase of flow rate,while that of relative velocities at the suction side near the pump shaft decreases.Radial vectors of absolute velocities and relative velocities change slightly under the two large flow rate conditions.The research results can be applied to instruct the hydraulic optimization design of double blade pumps.

急性冠脉综合征患者血清sST2及NLRP3水平与介入术后无复流-慢血流的相关性分析

目的探讨急性冠脉综合征(acute coronary syndrome,Acs)患者血清可溶性生长刺激表达基因蛋白2(soluble growth stimulation expression gene 2 protein,sST2),核苷酸寡聚化结构域样受体热蛋白结构域相关蛋白3(nucleotide oligomerization domain like receptor heat protein domain associated protein 3,NLRP3)水平与经皮冠状动脉介入治疗(percutaneous coronary intervention,PCI)术后无复流-慢血流的关系。方法选择2020年1月~2022年12月佳木斯市中心医院收治的97例急性冠脉综合征患者,所有患者均接受PCI治疗,根据术后无复流-慢血流发生情况分为无复流-慢血流组(n=20)和对照组(n=77)。术前检测血清sST2及NLRP3水平,分析影响急性冠脉综合征患者PCI术后无复流-慢血流的因素以及sST2,NLRP3预测急性冠脉综合征患者PCI术后无复流-慢血流的价值。结果无复流-慢血流组血清sST2(14.32±2.65 ng/ml vs 11.02±2.13 ng/ml),NLRP3(68.23±10.17 pg/ml vs 42.05±8.23 pg/ml)水平高于对照组,差异具有统计学意义(t=5.860,12.055,均P<0.05)。多因素Logistic回归分析显示高血栓负荷(OR:7.791,95%CI:2.834~21.421)、高水平sST2(OR=2.071,95%CI:1.146~3.743)、高水平NLRP3(OR=2.008,95%CI:1.228~3.284)是急性冠脉综合征患者PCI术后无复流-慢血流的危险因素(均P<0.05)。sST2,NLRP3诊断急性冠脉综合征患者PCI术后无复流-慢血流的临界值分别为12.91ng/ml,55.39 pg/ml,曲线下面积分别为0.737,0.686,联合sST2,NLRP3诊断急性冠脉综合征患者PCI术后无复流-慢血流的曲线下面积为0.907,高于单独诊断(Z=2.662,2.856,均P<0.05)。结论急性冠脉综合征患者血清sST2,NLRP3水平增高与PCI术后无复流-慢血流的发生有关,联合检测sST2和NLRP3可提高对术后无复流-慢血流的诊断效能。

Numerical simulation of standing wave with 3D predictor-corrector finite difference method for potential flow equations

A three-dimensional （3D） predictor-corrector finite difference method for standing wave is developed. It is applied to solve the 3D nonlinear potential flow equa- tions with a free surface. The 3D irregular tank is mapped onto a fixed cubic tank through the proper coordinate transform schemes. The cubic tank is distributed by the staggered meshgrid, and the staggered meshgrid is used to denote the variables of the flow field. The predictor-corrector finite difference method is given to develop the difference equa- tions of the dynamic boundary equation and kinematic boundary equation. Experimental results show that, using the finite difference method of the predictor-corrector scheme, the numerical solutions agree well with the published results. The wave profiles of the standing wave with different amplitudes and wave lengths are studied. The numerical solutions are also analyzed and presented graphically.

Nonlinear fluid flow through three-dimensional rough fracture networks:Insights from 3D-printing,CT-scanning,and high-resolution numerical simulations

Nonlinear flow behavior of fluids through three-dimensional(3D)discrete fracture networks(DFNs)considering effects of fracture number,surface roughness and fracture aperture was experimentally and numerically investigated.Three physical models of DFNs were 3D-printed and then computed tomography(CT)-scanned to obtain the specific geometry of fractures.The validity of numerically simulating the fluid flow through DFNs was verified via comparison with flow tests on the 3D-printed models.A parametric study was then implemented to establish quantitative relations between the coefficients/parameters in Forchheimer’s law and geometrical parameters.The results showed that the 3D-printing technique can well reproduce the geometry of single fractures with less precision when preparing complex fracture networks,numerical modeling precision of which can be improved via CT-scanning as evidenced by the well fitted results between fluid flow tests and numerical simulations using CT-scanned digital models.Streamlines in DFNs become increasingly tortuous as the fracture number and roughness increase,resulting in stronger inertial effects and greater curvatures of hydraulic pressure-low rate relations,which can be well characterized by the Forchheimer’s law.The critical hydraulic gradient for the onset of nonlinear flow decreases with the increasing aperture,fracture number and roughness,following a power function.The increases in fracture aperture and number provide more paths for fluid flow,increasing both the viscous and inertial permeabilities.The value of the inertial permeability is approximately four orders of magnitude greater than the viscous permeability,following a power function with an exponent a of 3,and a proportional coefficient b mathematically correlated with the geometrical parameters.