枸杞花药发育基因LbMS2的克隆及表达分析

MS2(Male sterily2)类基因编码脂肪酰基还原酶,参与了花药绒毡层中脂类代谢过程。该研究以宁夏枸杞(‘宁杞1号’)为试验材料,采用RACE方法从枸杞花药cDNA中获得枸杞LbMS2基因。结果显示,LbMS2基因开放阅读框为1 782bp,编码593个氨基酸,等电点为8.98;生物信息学分析显示,LbMS2蛋白定位于叶绿体;LbMS2蛋白序列与茄科植物矮牵牛、茸毛烟草、马铃薯、番茄以及甜辣椒中的MS2蛋白表现出较高的序列相似性;实时荧光定量PCR结果显示,LbMS2基因具有器官表达特异性,只在枸杞花器官中表达,并且在枸杞花药发育的四分体时期以及单核花粉时期表达量最高。研究表明,LbMS2基因是枸杞花器官发育过程中的重要基因。

Imbibition Front and Phase Distribution in Shale Based on Lattice Boltzmann Method

To study the development of imbibition such as the imbibition front and phase distribution in shale,the Lattice Boltzmann Method(LBM)is used to study the imbibition processes in the pore-throat network of shale.Through dimensional analysis,four dimensionless parameters affecting the imbibition process were determined.A color gradient model of LBM was used in computation based on a real core pore size distribution.The numerical results show that the four factors have great effects on imbibition.The impact of each factor is not monotonous.The imbibition process is the comprehensive effect of all aspects.The imbibition front becomes more and more non-uniform with time in a heterogeneous pore-throat network.Some non-wetting phases(oil here)cannot be displaced out.The displacement efficiency and velocity do not change monotonously with any factor.The development of the average imbibition length with time is not smooth and not linear in a heterogeneous pore-throat network.Two fitting relations between the four dimensionless parameters and the imbibition velocity and efficiency are obtained,respectively.

微纳米孔隙内气体流动特性与LBM数值模拟研究

目的研究瓦斯气体在煤层中的流动特性对于揭示煤层瓦斯赋存机理和扩散运移特性具有重要意义。煤中微纳米级孔隙结构十分复杂,为研究煤层瓦斯气体在微纳米孔隙中的流动特性,方法以均质纳米多孔炭薄膜为测试对象,采用扫描电镜实验对其孔隙大小和孔隙率进行定性定量分析;利用纳米尺度气体流动特征实验装置开展微纳米孔隙的气体流动实验研究,通过对比分析传统达西渗流模型和适用于微尺度下气体流动模型,结果得到更为详细的微纳米孔隙内气体流动特性:纳米多孔炭薄膜的视渗透率随着进气口压力的升高而下降,二者呈负相关的线性变化规律;视渗透率随着努森数降低而降低,二者呈正相关的线性变化规律,表明气体在微纳米尺度下的流动不符合传统的达西定律,滑脱效应和气体扩散不可忽视。采用格子Boltzmann方法(lattice boltzmann method,LBM)模拟不同进气口压力下的气体流动,得到不同气体压力下出口的气体流量,与实验结果进行对比,LBM模拟的平均误差为8.25%,整体吻合性较好,表明LBM数值模拟可有效揭示气体在微纳米尺度下的流动特性。结论研究结果可为今后分析煤层中的瓦斯流动机制和流动规律提供理论借鉴。

Effect of fracture fluid flowback on shale microfractures using CT scanning

The field data of shale fracturing demonstrate that the flowback performance of fracturing fluid is different from that of conventional reservoirs,where the flowback rate of shale fracturing fluid is lower than that of conventional reservoirs.At the early stage of flowback,there is no single-phase flow of the liquid phase in shale,but rather a gas-water two-phase flow,such that the single-phase flow model for tight oil and gas reservoirs is not applicable.In this study,pores and microfractures are extracted based on the experimental results of computed tomography(CT)scanning,and a spatial model of microfractures is established.Then,the influence of rough microfracture surfaces on the flow is corrected using the modified cubic law,which was modified by introducing the average deviation of the microfracture height as a roughness factor to consider the influence of microfracture surface roughness.The flow in the fracture network is simulated using the modified cubic law and the lattice Boltzmann method(LBM).The results obtained demonstrate that most of the fracturing fluid is retained in the shale microfractures,which explains the low fracturing fluid flowback rate in shale hydraulic fracturing.

An MPI parallel DEM-IMB-LBM framework for simulating fluid-solid interaction problems

The high-resolution DEM-IMB-LBM model can accurately describe pore-scale fluid-solid interactions,but its potential for use in geotechnical engineering analysis has not been fully unleashed due to its prohibitive computational costs.To overcome this limitation,a message passing interface(MPI)parallel DEM-IMB-LBM framework is proposed aimed at enhancing computation efficiency.This framework utilises a static domain decomposition scheme,with the entire computation domain being decomposed into multiple subdomains according to predefined processors.A detailed parallel strategy is employed for both contact detection and hydrodynamic force calculation.In particular,a particle ID re-numbering scheme is proposed to handle particle transitions across sub-domain interfaces.Two benchmarks are conducted to validate the accuracy and overall performance of the proposed framework.Subsequently,the framework is applied to simulate scenarios involving multi-particle sedimentation and submarine landslides.The numerical examples effectively demonstrate the robustness and applicability of the MPI parallel DEM-IMB-LBM framework.

Oldroyd-B黏弹性液滴撞击弯曲壁面的数值研究

液滴撞击弯曲壁面现象广泛存在于冶金、化工和航空航天等领域,在某些场景下,液滴混入高分子聚合物后会表现黏弹性特性,为了进一步认识液滴黏弹性对撞击弯曲壁面的影响,对黏弹性液滴撞击弯曲壁面的过程进行数值模拟研究.研究基于相场方法和格子玻尔兹曼(LBM)方法,采用应力场分布函数求解Oldroyd-B本构方程,并施加适用于弯曲壁面的接触角模型,发展了固-液-气三相黏弹性流体模拟方法,对Oldroyd-B黏弹性液滴撞击弯曲壁面问题进行数值模拟,主要研究了黏度比β、韦伯数We和壁面接触角θ对撞击过程的影响.结果表明:撞击过程主要包括4个阶段:运动阶段、铺展阶段、拉伸阶段和撕裂阶段.黏度比β越低,液滴在铺展拉伸阶段动能衰减越慢,转化的表面能更多,但更早进入撕裂阶段,液滴撞击弯曲壁面后,更容易脱离壁面.韦伯数We较小时,液滴主要在壁面处附着或反弹;We较大时,液滴会撕裂并脱离壁面,We越大,液滴在铺展拉伸阶段动能衰减越快,进入撕裂阶段更慢.壁面的亲疏水性会影响液滴最终的状态,疏水性越高,对铺展阶段的阻碍作用越强,液滴越容易发生撕裂和脱离.

基于LBM的海上低渗油藏水驱后烃气驱动用机理及提采效果研究

海上低渗油藏水驱后孔隙中仍存在大量剩余油,采用烃气驱可进一步提高采收率,但动用机理尚不明确。以南海北部湾海域涠洲12-1油田为研究对象,根据铸体薄片实验结果抽提孔隙特征,利用格子玻尔兹曼微观孔隙尺度模拟方法,开展了水驱后烃气驱微观模拟,探究水驱后剩余油分布特征、烃气驱对剩余油的动用机理及不同气驱方式对驱油效果的影响。结果表明:水驱后孔隙中剩余油主要以并联孔道、膜状、盲端孔隙、小孔喉盲端孔隙等形式赋存;注入烃气可通过溶解萃取、原油膨胀、改善流道等动用剩余油,提高波及系数;烃气与原油混相时,气体突破时间延后25.29%,波及系数提高24.87%;不同注气方式中水气交替驱替效果最好,注入水可有效封堵高渗通道,提升注入气利用率,以1:1的水气段塞时注入气利用率可提升41.43%。该研究对海上低渗油藏水驱后烃气驱开发具有理论指导意义。

An inverse analysis of fluid flow through granular media using differentiable lattice Boltzmann method

This study presents a method for the inverse analysis of fluid flow problems.The focus is put on accurately determining boundary conditions and characterizing the physical properties of granular media,such as permeability,and fluid components,like viscosity.The primary aim is to deduce either constant pressure head or pressure profiles,given the known velocity field at a steady-state flow through a conduit containing obstacles,including walls,spheres,and grains.The lattice Boltzmann method(LBM)combined with automatic differentiation(AD)(AD-LBM)is employed,with the help of the GPU-capable Taichi programming language.A lightweight tape is used to generate gradients for the entire LBM simulation,enabling end-to-end backpropagation.Our AD-LBM approach accurately estimates the boundary conditions for complex flow paths in porous media,leading to observed steady-state velocity fields and deriving macro-scale permeability and fluid viscosity.The method demonstrates significant advantages in terms of prediction accuracy and computational efficiency,making it a powerful tool for solving inverse fluid flow problems in various applications.

A particle-resolved heat-particle-fluid coupling model by DEM-IMB-LBM

Multifield coupling is frequently encountered and also an active area of research in geotechnical engineering.In this work,a particle-resolved direct numerical simulation(PR-DNS)technique is extended to simulate particle-fluid interaction problems involving heat transfer at the grain level.In this extended technique,an immersed moving boundary(IMB)scheme is used to couple the discrete element method(DEM)and lattice Boltzmann method(LBM),while a recently proposed Dirichlet-type thermal boundary condition is also adapted to account for heat transfer between fluid phase and solid particles.The resulting DEM-IBM-LBM model is robust to simulate moving curved boundaries with constant temperature in thermal flows.To facilitate the understanding and implementation of this coupled model for non-isothermal problems,a complete list is given for the conversion of relevant physical variables to lattice units.Then,benchmark tests,including a single-particle sedimentation and a two-particle drafting-kissing-tumbling(DKT)simulation with heat transfer,are carried out to validate the accuracy of our coupled technique.To further investigate the role of heat transfer in particle-laden flows,two multiple-particle problems with heat transfer are performed.Numerical examples demonstrate that the proposed coupling model is a promising high-resolution approach for simulating the heat-particle-fluid coupling at the grain level.

Overall Assessment of Heat Transfer for a Rarefied Flow in a Microchannel with Obstacles Using Lattice Boltzmann Method

The objective of this investigation is to assess the effect of obstacles on numerical heat transfer and fluid flow momentum in a rectangular microchannel(MC).Two distinct configurations were studied:one without obstacles and the other with alternating obstacles placed on the upper and lower walls.The research utilized the thermal lattice Boltzmann method(LBM),which solves the energy and momentum equations of fluids with the BGK approximation,implemented in a Python coding environment.Temperature jump and slip velocity conditions were utilized in the simulation for the MC and extended to all obstacle boundaries.The study aims to analyze the rarefaction effect,with Knudsen numbers(Kn)of 0.012,0.02,and 0.05.The outcomes indicate that rarefaction has a significant impact on the velocity and temperature distribution.The presence of nine obstacles led to slower fluid movement inside the microchannel MC,resulting in faster cooling at the outlet.In MCs with obstacles,the rarefaction effect plays a crucial role in decreasing the Nusselt number(Nu)and skin friction coefficient(Cf).Furthermore,the study demonstrated that the obstacles played a crucial role in boosting fluid flow and heat transfer in the MC.The findings suggest that the examined configurations could have potential applications as cooling technologies in micro-electro-mechanical systems and microdevice applications.

基于LBM水力裂缝中支撑剂颗粒团簇升阻力系数研究

水力压裂中,裂缝壁面对支撑剂团在狭窄裂缝中输送沉降时的受力有重要影响。该文基于LBM建立颗粒流动数值模型,构建星型、三棱柱型、长方体型颗粒团簇模型,研究颗粒团簇在不同雷诺数Re、颗粒团簇与壁面相对距离H/d下的升阻力变化规律。结果表明:壁面影响下,随Re的增大,颗粒团簇的曳力系数、升力系数均减小,且壁面方向升力系数总小于无壁面方向的结果;单颗粒曳力系数与团簇平均曳力系数的比值随Re的增加而减小,随壁面边界效应的影响而增大;不同位置的颗粒曳力系数比值表现为前排颗粒减小、中间颗粒先增大后减小、近壁面颗粒逐渐增大。随H/d的增大,颗粒团簇远离壁面,边界影响减弱,曳力系数减小程度逐渐减弱;前排及近壁面颗粒曳力系数比值与升力系数随之减小;远壁面颗粒逐渐靠近壁面,曳力系数比值增大。壁面边界效应会加剧近壁面颗粒受力,且外侧颗粒对内部颗粒受力有屏蔽作用。

Exploration of the coupled lattice Boltzmann model based on a multiphase field model:A study of the solid-liquid-gas interaction mechanism in the solidification process

A multiphase field model coupled with a lattice Boltzmann(PF-LBM)model is proposed to simulate the distribution mechanism of bubbles and solutes at the solid-liquid interface,the interaction between dendrites and bubbles,and the effects of different temperatures,anisotropic strengths and tilting angles on the solidified organization of the SCN-0.24wt.%butanedinitrile alloy during the solidification process.The model adopts a multiphase field model to simulate the growth of dendrites,calculates the growth motions of dendrites based on the interfacial solute equilibrium;and adopts a lattice Boltzmann model(LBM)based on the Shan-Chen multiphase flow to simulate the growth and motions of bubbles in the liquid phase,which includes the interaction between solid-liquid-gas phases.The simulation results show that during the directional growth of columnar dendrites,bubbles first precipitate out slowly at the very bottom of the dendrites,and then rise up due to the different solid-liquid densities and pressure differences.The bubbles will interact with the dendrite in the process of flow migration,such as extrusion,overflow,fusion and disappearance.In the case of wide gaps in the dendrite channels,bubbles will fuse to form larger irregular bubbles,and in the case of dense channels,bubbles will deform due to the extrusion of dendrites.In the simulated region,as the dendrites converge and diverge,the bubbles precipitate out of the dendrites by compression and diffusion,which also causes physical phenomena such as fusion and spillage of the bubbles.These results reveal the physical mechanisms of bubble nucleation,growth and kinematic evolution during solidification and interaction with dendrite growth.

Passive particles driven by self-propelled particle:The wake effect

This work focuses on numerically studying hydrodynamic interaction between a passive particle and a self-propelled particle,termed a squirmer,by using a two-dimensional lattice Boltzmann method(LBM).It is found that the squirmer can capture a passive particle and propel it simultaneously,provided the passive particle is situated within the squirmer's wake.Our research shows that the critical capture distance,which determines whether the particle is captured,primarily depends on the intensity of the squirmer's dipolarity.The stronger dipolarity of squirmer results in an increased critical capture distance.Conversely,the Reynolds number is found to have minimal influence on this interaction.Interestingly,the passive particle,when driven by the squirmer's wake,contributes to a reduction in the squirmer's drag.This results in a mutual acceleration for both particles.Our findings can provide valuable perspectives for formulating the principles of reducing the drag of micro-swimmers and help to achieve the goal of using micro-swimmers to transport goods without physical tethers.

Wave propagation across fluid-solid interfaces with LBM-LSM coupling schemes

Seismic wave propagation in fluid-solid coupled media is currently a popular topic. However, traditional wave equation-based simulation methods have to consider complex boundary conditions at the fluid-solid interface. To address this challenge, we propose a novel numerical scheme that integrates the lattice Boltzmann method(LBM) and lattice spring model(LSM). In this scheme, LBM simulates viscoacoustic wave propagation in the fluid area and LSM simulates elastic wave propagation in the solid area. We also introduce three different LBM-LSM coupling strategies, a standard bounce back scheme, a specular reflection scheme, and a hybrid scheme, to describe wave propagation across fluid-solid boundaries. To demonstrate the accuracy of these LBM-LSM coupling schemes, we simulate wave propagation in a two-layer model containing a fluid-solid interface. We place excitation sources in the fluid layer and the solid layer respectively, to observe the wave phenomena when seismic waves propagate to interface from different sides. The simulated results by LBM-LSM are compared with the reference wavefields obtained by the finite difference method(FDM) and the analytical solution(ANA).Our LBM-LSM coupling scheme was verified effective, as the relative errors between the LBM-LSM solutions and reference solutions were within an acceptable range, sometimes around 1.00%. The coupled LBM-LSM scheme is further used to model seismic wavefields across a more realistic rugged seabed,which reveals the potential applications of the coupled LBM-LSM scheme in marine seismic imaging techniques, such as reverse-time migration and full-waveform inversion. The method also has potential applications in simulating wave propagation in complex two-and multi-phase media.

枸杞脂肪酰基还原酶基因的克隆及表达分析

脂肪酰基还原酶基因广泛参与植物的脂类代谢过程,影响植物雄配子体花药发育以及表皮蜡酯合成等。本研究利用RACE方法从宁夏枸杞(宁杞1号)花药中克隆脂肪酰基还原酶LbMS2-2基因,开放阅读框全长1800bp,编码599个氨基酸,等电点为9.00。生物信息学分析表明,LbMS2-2蛋白定位于叶绿体中,该蛋白序列与茄科植物甜辣椒、烟草和马铃薯中的脂肪酰基还原酶表现出较高的序列相似性;实时荧光定量PCR显示,LbMS2-2基因在枸杞花器官中表达,且在枸杞花药发育的四分体时期、单核花粉时期和双核花粉时期表达量较高。原位杂交结果证实该基因只在花药绒毡层和小孢子中表达。亚细胞定位结果进一步验证LbMS2-2基因的叶绿体定位。以上结果表明,枸杞脂肪酰基还原酶基因是枸杞花器官发育过程中的重要基因。

具有层状碱金属盐结构的氢氧化氨基苯甲酸锌的制备及表征

以自制的β-Zn(OH)2和氨基苯甲酸为原料,水热合成了具有层状碱金属盐(LBMS)结构的氢氧化氨基苯甲酸锌化合物。通过XRD、TG-DTA、SEM和TEM分析研究了合成产物的结构、形貌和热稳定性,探讨了合成条件对水热反应产物的影响及合成产物在有机溶剂中的剥离反应。当o-NH2C6H4COOH/Zn的摩尔比为1.2,水热温度70℃下反应12h时,得到的层状物具有板块状粒子特征,层间距为1.33nm;当m-NH2C6H4COOH/Zn的摩尔比为1.8,水热温度40℃下反应24h时,得到的层状化合物具有纤维状粒子特征,层间距为1.08nm。合成的层状物在醇溶剂中可发生剥离反应,层状氢氧化邻氨基苯甲酸锌在正丁醇中的剥离量为0.12g.L-1,层状氢氧化间氨基苯甲酸锌在乙醇中的剥离量为0.18g·L-1。

基于LBM方法的圆盘等速入水空泡的数值模拟

采用单相格子Boltzmann模型进行了物体垂直入水问题的研究。该模型适用于大密度比的气液两相流动,其特点是忽略了系统中气相对液相的动力学影响。模拟了圆盘垂直等速入水过程,给出了入水过程中空泡与自由面的变化规律,研究了圆盘入水空泡相对闭合深度与Froude数之间的关系。数值模拟结果与相关的实验结果吻合良好,验证了格子Boltzmann方法(LBM:Lattice Boltzmann Method)模拟物体入水问题的可行性。

流体真实性仿真的国内外研究进展

介绍近二十年来流体真实性仿真的研究进展,分别从底层开发和基于平台开发两个方面阐述了目前流体真实性仿真主要研究方法。从Navier-Strokes和Lattice Boltzmann method(LBM)两个方面介绍了基于底层开发的流体模拟算法及其实现方式;总结了基于平台开发的流体真实性模拟主流工具及其实现效果。在对各种方法进行分析对比的基础上,对流体真实性仿真的研究方式与思路进行了探讨,指出了流-体真实性仿真的研究热点与发展趋势。

多孔介质中两相驱离的格子Boltzmann模型新研究

利用粒子之间相互作用 ,即同种物质粒子相互吸引 ,异种物质粒子相互排斥这一物理化的原理研究并提出了一个新型的模拟多孔介质中二相驱离的格子玻耳兹曼模型 ,结果表明它能有效地模拟多孔介质中的二相驱离问题 ,且节省机时 ,分界面上涨落也小 。

含裂隙煤体瓦斯渗流规律的LBM数值模拟

通过模拟外力驱动渗流以及部分填充多孔介质的剪切渗流,验证了广义LBM模型可以对含有裂隙的煤体内瓦斯渗流规律进行模拟研究;裂隙内的流速明显高于在煤基质内的流速,定量研究了渗流速度和流量随着裂隙宽度增加的变化规律;而在裂隙宽度相等的条件下,煤体渗透率越低则流速和流量的提高越显著;与顺流向的裂隙相比,垂直流向裂隙的存在对提高渗流速度及流量的影响相对较为有限。模拟结果表明:裂隙的存在,尤其是在渗透性较差的煤层中,对提高瓦斯抽放的效果更为明显;而对于不同方向的裂隙,则应该重点关注与瓦斯流动方向相同或大体相同的裂隙分布。