模拟水体镉污染对水稻种子萌发的影响

镉对作物生长发育具有毒害作用。实验结果表明 ,水稻种子在萌发期间对水体镉污染产生明显反应 :镉离子浓度较低 ( 5mg/L以下 )时呈暂时的促进作用 ;镉离子浓度较高 ( 30mg/L)时 ,表现为抑制作用 ,且随浓度不断提高这种抑制作用逐渐加强 ;镉离子浓度更高 ( 30 0mg/L)时 ,生长点坏死 ,根本不萌发。对镉离子的反应 ,胚根比胚芽敏感 ,α -淀粉酶比 β

模拟水体湍流环境下目标激光点云数据的三维重建与分析

水下目标三维点云重建在水底勘探和水下无人航行器避障等领域有着重要的应用。本文通过实验室模拟温度和盐度水体湍流,开展了水下目标探测实验,研究了温度差和盐度差对水下潜艇、滑翔机和锚雷的激光点云三维重建效果的影响,并对重建后的三维点云数据进行误差分析。结果表明:在水下目标三维点云重建过程中,随着水体温度湍流和盐度湍流强度的增强,重建点云数据的有效点数明显下降,均值误差明显上升。研究结果对水下三维点云重建系统的研制具有一定参考价值。

模拟水体流动的软件包

本文介绍了一种便于应用的模拟水体流动的软件包，用它可以对修建堰坝以后的水流情况给出可靠的预报。

底泥盐分释放影响下的滨海水库水体盐度变化过程数值模拟

为研究滨海水库大尺度水体盐度时空动态变化,改进了水动力与水环境数值模拟专业模型Delft3D中盐度输运方程的源汇项,对所得的数学模型计算值与理论值和实验值进行对比分析,并验证其合理性。结果表明,将改进后的Delft3D模型应用于拟建滨海水库的盐度变化过程模型,能定量预测不同工况情形下水库底泥盐分释放造成的盐度变化过程。

一种改进的基于数字高程模型的水体覆盖范围模拟方法

实时获取水体空间覆盖范围,对于灾害的防治、水资源的合理调配具有重要的意义。基于数字高程模型和实测水位数据模拟水体覆盖范围的方法具有简单易实现的特点,已有研究通常采用单一水位值作为参数,该文考虑水位的空间分布,对现有方法进行改进,提出了基于实测水位空间插值的水体淹没范围模拟方法。通过在鄱阳湖入江水道这一水体动态特征明显的区域进行水域范围模拟实验,对方法的精度进行了综合评价。结果表明该文方法能够有效模拟水体范围,相比现有方法模拟精度提高,当水位空间分布差异较大时,这一优势更为明显。这一研究成果对水资源综合管理相关研究与实际工作具有较为重要的实用参考价值。

近海水体富营养化条件下氮·磷对浒苔生长的影响

[目的]研究氮、磷营养元素对浒苔生长的影响,为减轻近海富营养化水体浒苔危害提供科学依据。[方法]以尿素与三聚磷酸钠(STTP)作为氮素与磷素的来源,模拟近海水体富营养化环境,研究氮、磷营养条件下浒苔鲜重和生长速率的变化。[结果]浒苔在氮、磷营养不充足的条件下生长较慢,加氮与加磷的处理均能促进浒苔的生长,加氮的处理对浒苔生长的影响较加磷大,而加氮与磷的处理影响最为明显,且氮、磷充足处理的浒苔发育加快。[结论]保护好近海水资源,减少氮、磷输入是减轻浒苔危害的可行途径。

水体注入器皿的动力学粒子建模研究

基于物理过程的建模方式能够真实地模拟流体的运动状态,表现出很好的模拟效果,但对不同的流体形态以及同一种流体的不同细节状况,所涉及到的细节属性参数也不同,通常存在着较大的建模差异。首先对流体动力学的流体模拟原理进行了分析,在此基础上对水体倒入4种不同形状容器的流体动力学平滑粒子模型进行了研究,提出一种基于分块的邻居粒子搜索方法,以提高在空间均匀网格上对邻居粒子的搜索速度,给出了流体与器皿碰撞的判断与响应方法。最后通过水体注入不同器皿的仿真试验验证了所建立模型的有效性。

基于Hydrolight模型的太湖SDGSAT-1卫星悬浮物浓度反演研究

利用卫星遥感反演水体中的悬浮物浓度对水质监测和保护具有重要意义,在悬浮物浓度反演过程中,如何避免或最大程度降低水体中叶绿素a、有色可溶性有机物(Colored Dissolved Organic Matter,CDOM)的干扰是当前的技术难点。文章针对可持续发展科学卫星1号(SDGSAT-1)MII传感器,利用Hydrolight辐射传输模型,从理论上挖掘只与悬浮物强相关的反演因子,以此构建适用于MII影像的太湖悬浮物浓度反演模型,通过水体的实测数据和遥感数据对模型应用效果进行验证。结果表明:反演因子R′(B_5/B_3)与悬浮物浓度为强相关,同时与叶绿素a、CDOM浓度弱相关;利用R′(B_5/B_3)作为反演因子构建的幂函数模型为最优反演模型;将幂函数模型分别应用于实测数据和2022年5月4日的太湖SDGSAT-1 MII数据,两次验证试验显示反演结果和现场测量结果具有较强一致性,模型适用性较好。该研究可为SDGSAT-1卫星在湖泊水体悬浮物浓度监测、水资源评估与保护等提供一些技术参考。

贵州省环境因素与霍乱弧菌生存关系的研究

目的 探索霍乱弧菌在贵州人群及外环境中的生存情况 方法 对人群带菌情况及曾是霍乱疫区外环境进行检测，在模拟自然水体中观察霍乱弧菌的生存 结果 未在人群及外环境发现霍乱弧菌，模拟自然水体中霍 乱弧菌能存活不到2个月。结论 霍乱弧菌不能在贵州生态环 境下生存越冬，不能在人体胆囊长期生存。

模拟真实水体环境下目标激光点云数据的三维重建与分析

水下目标探测在水下事故搜救、设备维护以及资源勘探等领域有重要的应用。通过实验模拟了两种典型海域的水体环境,研究了盐度和浊度这两个水体物理特性参数以及探测距离对水下潜艇、滑翔机和锚雷的激光点云三维重建效果的影响,并将重建后的三维点云数据和三种模型的标准点云进行对比并分析误差。结果表明:盐度变化对水下目标三维点云重建的影响较小,平均误差变化范围在1 mm以内;浊度增大会增强水体的后向散射影响,对成像有较大的干扰,有效点数显著减少;随着探测距离的增大,均值误差呈线性上升,目标点云图像的轮廓变得模糊。

CFD simulation of gas–liquid flow in a high-pressure bubble column with a modified population balance model

In this study,based on the Luo bubble coalescence model,a model correction factor C_e for pressures according to the literature experimental results was introduced in the bubble coalescence efficiency term.Then,a coupled modified population balance model(PBM) with computational fluid dynamics(CFD) was used to simulate a high-pressure bubble column.The simulation results with and without C_e were compared with the experimental data.The modified CFD-PBM coupled model was used to investigate its applicability to broader experimental conditions.These results showed that the modified CFD-PBM coupled model can predict the hydrodynamic behaviors under various operating conditions.

An Improved Level Set Approach to the Simulation of Drop and Bubble Motion

An improved level set approach for computing the incompressibletwo-phase flow with significantly de- formed free interface ispresented. The control volume formulation with the semi-implicitmethod for pressure-linked equations consistent (SIMPLEC) algorithmincorporated is used to solve the governing equations on a staggeredgrid. Several improvements concerning the computational grid,interface update, reinitialization procedure etc. are tested Andfound to be effective in promoting the convergence and numericalstability.

Numerical simulation analysis by solid-liquid coupling with 3DEC of dynamic water crannies in overlying strata

To solve the problem of water loss during mining of shallow, buried coal seams, we have first analyzed the mechanism and suitability of solid-liquid coupling, i.e., we used the FLUID-MECHANICS system of 3-Dimensional Distinct Element Code (3DEC) in simulating dynamic water crannies in overlying strata, under mining conditions of a large longwall coalface. Next the dynamic initiation of a water cranny, its propagation and close phases were studied with 3DEC, along with the overlying strata breakage and recombination as the mining space of the shallow, buried coal seam increased. Combined with the change in the stress and displacement fields, the distribution features of the mining cranny were systematically studied. The effect of regularities and their effective measures of local filling and mine slicing technology in controlling mine crannies were investigated and the potential danger areas of water loss identified. Our results can be applied to decrease water loss during the exploitation of shallow, buried coal seams with a thin bedrock. The results also prove that 3DEC is a credible numerical analytical method to predict initiations of dynamic water crannies, their propagation, their closure phases and other concomitant hazards.

Simulation of Cavitating Flow around a 2-D Hydrofoil

In order to predict the effects of cavitation on a hydrofoil, the state equations of the cavitation model were combined with a linear viscous turbulent method for mixed fluids in the computational fluid dynamics (CFD) software FLUENT to simulate steady cavitating flow. At a fixed attack angle, pressure distributions and volume fractions of vapor at different cavitation numbers were simulated, and the results on foil sections agreed well with experimental data. In addition, at the various cavitation numbers, the vapor fractions at different attack angles were also predicted. The vapor region moved towards the front of the airfoil and the length of the cavity grew with increased attack angle. The results show that this method of applying FLUENT to simulate cavitation is reliable.

Numerical Simulation of the Water Entry of a Structure in Free Fall Motion

To solve the problems concerning water entry of a structure, the RANS equations and volume of fluid （VOF） method are used. Combining the user-defined function （UDF） procedure with dynamic grids, the water impact on a structure in free fall is simulated, and the velocity, displacement and the pressure distribution on the structure are investigated. The results of the numerical simulation were compared with the experimental data, and solidly consistent results have been achieved, which validates the numerical model. Therefore, this method can be used to study the water impact problems of a structure.

CFD-PBE simulation of a bubble column in OpenFOAM

A general CFD-PBE(computational fluid dynamics-population balance equation) solver for gas–liquid poly-dispersed flows of both low and high gas volume fractions is developed in OpenFOAM(open-source field operation and manipulation) in this work. Implementation of this solver in OpenFOAM is illustrated in detail. The PBE is solved with the cell average technique. The coupling between pressure and velocity is dealt with the transient PIMPLE algorithm, which is a merged PISO-SIMPLE(pressure implicit split operator-semi-implicit method for pressure-linked equations) algorithm. Results show generally good agreement with the published experimental data, whereas the modeling precision could be improved further with more sophisticated closure models for interfacial forces, the models for the bubble-induced turbulence and those for bubble coalescence and breakage.The results also indicate that the PBE could be solved out the PIMPLE loop to save much computation time while still preserving the time information on variables. This is important for CFD-PBE modeling of many actual gas–liquid problems, which are commonly high-turbulent flows with intrinsic transient and 3 D characteristics.

Numerical simulations of water flow and contaminants transport near mining wastes disposed in a fractured rock mass

A numerical tool, called Hydro-Geosphere, was used to simulate unsaturated water flow and contaminants migration around an open pit filled with mining wastes. Numerical simulations had been carried out to assess the influence of various factors on water flow and solute transport in and around the surface openings including recharge, properties of the waste material and presence of fractures in the surrounding rock mass. The effect of the regional hydraulic gradient was also investigated. The analyses were conducted by simulating various 2D cases using experimentally obtained material properties and controlled boundary conditions. The effects of the hydrogeological properties of the filling material(i.e., water retention curve and hydraulic conductivity function), fracture network characteristics and conductivity of the joints were assessed. The results illustrate that fractures control water flow and contaminants transport around the waste disposal area. A fracture network can desaturate the system and improve the regional gradient effect.

CFD-Based Numerical Simulation of Water Film Flash Evaporation with a New Flash Evaporation Model

In this study, a new mass model involving superheat, initial temperature, liquid height, evaporator diameter, and flashing time is established to describe the flash evaporation process of water film. Of 469 sets of flash experimental data from three previous researches, 305 sets were applied to optimize parameters, and the other 164 sets were used to verify the practicability of the model. The results showed that the mean relative error between the literature data and the model values was less than 16.3%, and the model statistics proved that the model was well-posed. Then, the kinetic model was obtained using the time derivative of the new mass model. Computational fluid dynamics simulation of water film flash evaporation was studied based on a user-defined function program of the new evaporation kinetic model. The new kinetic model shows more consistency with the experimental phenomena in terms of evaporated mass and temperature compared with the evaporation–condensation model in Fluent software and Gopalakrishna's model. This new kinetic model can be extended to describe the flash process of water solution under other conditions.

Reflection and Transmission of the Level Step to the Waves in a Linear and Continuous Layer Liquid

The reflection and transmission of the level step to the water waves in the linear and continuous layer liquid were studied in this paper. Based on the matching method of the eigenfunction and a Boussinesq approximation, the analytical expression of the diffraction was obtained and the computing methods of the reflection and transmission en- ergy of the level step were proposed. For the incident wave with a frequency greater than that of the flotage, there is only one mode of plane traveling wave in the flow field. In the range of this greater frequency, the linear and continuous delamination effect will affect the reflection and transmission energy of the floating rectangular box. When the fre- quency of the incident wave is less than the flotage frequency, the energy of the plane traveling wave with infinite modes in the flow field will change into the energy of different modes for each incident wave of different modes.

In vitro simulation studies of silica deposition induced by lignin from rice

To reveal the possible mechanism of silica deposition in higher plants, lignin was isolated from rice straw following a modified method to conduct a simulation experiment in vitro. UV and infrared absorption spectra showed that the substance had the unique characteristics of pure lignin. The presence of silicon in the precipitation was revealed by TEM (transmission electron microscopy) with EDXA (energy dispersive X-ray analysis) device. It was found that in the borax solution where lignin precipi-tation occurred silica-lignin co-precipitation was produced but not in the DMSO solution where lignin was broken into its com-position compounds and did not precipitate. This means that it is macromolecular lignin itself but not its compounds that could induce silica deposition in higher plants.