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Objective: Genetic mutations of fused in sarcoma (FUS) causing amyotrophic lateral sclerosis (ALS) may disrupt mRNA splicing events. For example, the FUS c.1394-2delA variant was reported in two western ALS patients, but its molecular mechanism is unclear. In this study, we aim to investigate FUS splice site mutations in Chinese ALS patients. Methods: Sanger sequencing was used to identify FUS splicing mutations in Chinese ALS patients. We combined a deep learning tool (SpliceAI), RNA sequencing, and RT-PCR/RT-qPCR to analyze the effect of FUS c.1394-2delA mutation on RNA splicing and expression. AlphaFold was used to predict the protein structure of mutant FUS. In transfected cell lines, we used immunofluorescence to assess cytoplasmic mislocalization of mutant FUS protein. Results: We identified a de novo FUS splice acceptor site mutation (c.1394-2delA, p. Gly466Valfs*14) in one Chinese sporadic ALS patient, which is linked to exon 14 skipping, and upregulated total FUS mRNA expression. The FUS splice site mutation was predicted to be translated into a truncated protein product at C-terminal. In vitro studies revealed that the FUS mutation increased cytoplasmic mislocalization in both HEK293T and SH-SY5Y cells. Conclusions: We identified a de novo FUS splicing mutation (c.1394-2delA, p. Gly466Valfs*14) in 1 out of 233 Chinese ALS patients. It caused abnormal RNA splicing, upregulated gene expression, truncated FUS translation, and cytosolic mislocalization. Our findings suggested that FUS splice site mutation is rare in Chinese ALS patients and extended our knowledge of molecular mechanisms of the FUS c.1394-2delA mutation.

Aging is the strongest risk factor for Parkinson's disease (PD), which is a clinically heterogeneous movement disorder with highly variable age at onset. DNA methylation age (DNAm age) is an epigenetic clock that could reflect biological aging.The aim was to evaluate whether PD age at onset is associated with DNAm-age acceleration (difference between DNAm age and chronological age).We used the genome-wide Infinium MethylationEPIC array to assess DNAm age in discovery (n = 96) and replication (n = 182) idiopathic PD cohorts and a unique longitudinal LRRK2 cohort (n = 220) at four time points over a 3-year period, comprising 91 manifesting and 129 nonmanifesting G2019S carriers at baseline. Cox proportional hazard regression and multivariate linear regression were used to evaluate the relation between DNAm-age acceleration and PD age at onset, which was highly variable in manifesting G2019S carriers (36-75 years) and both idiopathic PD cohorts (26-77 and 35-81 years).DNAm-age acceleration remained steady over the 3-year period in most G2019S carriers. It was strongly associated with age at onset in the LRRK2 cohort (P = 2.25 × 10This study is the first to demonstrate that DNAm-age acceleration is related to PD age at onset, which could be considered in disease-modifying clinical trials. Future studies should evaluate the stability of DNAm-age acceleration over longer time periods, especially for phenoconverters from nonmanifesting to manifesting individuals. © 2022 International Parkinson and Movement Disorder Society.

Spinocerebellar ataxia type 3 (SCA3), also known as Machado Joseph disease (MJD), is a common dominantly inherited ataxia, and has heterogeneous clinical features and variable age of onset, ranging from 10 to 78 years. Repeats variability of ATXN3, HTT, ATN1 and ATXN2 can explain partially but not fully SCA3 age of onset heterogeneity. Aging is a reported modifier of SCA3 severity and closely linked to DNA methylation (DNAm). DNAm age acceleration was associated with disease risk and/or variable disease phenotypes in several repeat associated neurodegenerative diseases (such as Huntington's disease and Amyotrophic lateral sclerosis). To understand if DNAm age acceleration is associated with SCA3 age of onset, we performed a genome-wide DNAm study of a Chinese SCA3 family with variable age of onset and clinical presentations. All patients showed unsteady gait, deterioration of extremities coordination, speech (dysarthria) and swallowing problems (dysphagia, choking on eating and/or drinking) and oculomotor abnormalities, with variable age of onset ranging from 27 to 52 years. We found that DNAm age acceleration is associated with age of onset (p-value = 0.0023, B = -1.26), suggesting that every 5 year increase in DNAm-age acceleration is corresponding to a 6.3 year earlier disease onset. This association remains significant after the adjustment to ATXN3 CAG repeats (adjusted p-value = 0.037, adjusted B = -1.0). In an independent SCA3 cohort (n = 40), we also observed the association between DNAm age acceleration and age of onset (adjusted p-value = 0.007, adjusted B = -0.69). Of note, we found no significant association between DNAm of single-CpG locus and/or CpG-SNPs and SCA3 age of onset in the current family or the SCA3 cohort. Our findings suggested that DNAm age acceleration might be a SCA3 age of onset modifier, and encourage further investigations in extended SCA3 cohorts to clarify the role of epigenetic aging in modifying disease onset.

Non-O157 Shiga toxin (stx)–producing Escherichia coli (STEC) is recognized as an important human diarrheal pathogen. Cattle are the principal reservoirs of STEC, although other animals can be carri...

Parkinson’s disease is a clinically and genetically heterogeneous movement disorder with highly variable age-at-onset. DNA methylation (DNAm) age is an epigenetic clock that could reflect biological aging. Studies of DNAm-age acceleration (difference between DNAm-age and chronological age) are pertinent to neurodegenerative diseases (e.g., Parkinson’s disease), for which aging is the strongest risk-factor. We assessed DNAm-age in idiopathic Parkinson’s disease (n=96) and a longitudinal LRRK2 cohort at four time-points over a 3-year period (n=220), including manifesting (n=91) and non-manifesting (n=129) G2019S-carriers. A highly variable age-at-onset was observed in both the idiopathic cohort (26-77 years) and manifesting G2019S-carriers (39-79 years). Increased DNAm-age acceleration was significantly associated with younger onset in idiopathic and LRRK2-related Parkinson’s disease, suggesting that every 5-year increase in DNAm-age acceleration is linked to about 6-year earlier onset. At an individual level, DNAm-age acceleration remained steady over a 3-year period for most G2019S-carriers, indicating that it might serve as a stable biomarker of biological aging. Future studies should evaluate the stability of DNAm-age acceleration over longer time-periods, especially for phenoconverters from non-manifesting to manifesting subjects. In conclusion, DNAm-age acceleration is linked to disease onset, and could be used in disease-modifying clinical trials of prodromal Parkinson’s disease.

Diabetes is characterized by pancreas dysfunction and is commonly associated with obesity. Hypoglycemic agents capable of improving β-cell function and reducing body weight therefore are gaining increasing interest. Though glucagon-like peptide 1 receptor (GLP-1R)/cholecystokinin 2 receptor (CCK-2R) dual agonist ZP3022 potently increases β-cell mass and improves glycemic control in diabetic db/db mice, the in vivo half-life (t1/2) is short, and its body weight reducing activity is limited. Here, we report the discovery of a series of novel GLP-1R/CCK-2R dual agonists. Starting from Xenopus GLP-1, dual cysteine mutation was conducted followed by covalent side chain stapling and albumin binder incorporation, resulting in a stabilized secondary structure, increased agonist potency, and improved stability. Further C-terminal conjugation of gastrin-6 generated GLP-1R/CCK-2R dual agonists, among which 6a and 6b showed higher stability and hypoglycemic activity than liraglutide and ZP3022. Desirably, 6a and 6b exhibited prominent metabolic benefits in diet-induced obesity mice without causing nausea responses and exerted considerable effects on β-cell restoration in db/db mice. These preclinical studies suggest the potential role of GLP-1R/CCK-2R dual agonists as effective agents for treating diabetes and related metabolic disorders.

An experimental study to investigate various features of subsurface vortices and their evolutions inside a closed pump intake under different pressure conditions at free surface, and to analyze the influence of a pipe bell with different mean axial velocities at the same water level on flow patterns is presented. For all cases, three different flow regimes are closely observed: various side-wall attached, back-wall attached and submerged vortices structures, and their evolutions are subject to the free-surface pressure for a critical flow rate, the number and strength of all these vortex rise as the absolute value of the pressure increases for a higher flow rate, for a lower flow rate, whether the side-wall vortices occur or not is related closely to the pressure magnitude, and there are no vortices for lower absolute pressure values, the number and the strength of the side-wall vortices increase as the absolute pressure values increase. Besides, based on statistical analyses, the side-wall vortex probability on the right side along the stream-wise direction is much higher than that on the opposite side for all operation cases, particularly single vortex probability, and the back-wall vortex probabilities are quite higher with values of more than 90%, meanwhile, the multi-vortices probability is much higher than that of the single-vortex. The captured vortices have been qualitatively classified into different “vortex zones”: no vortex zones and vortex zones including transition, single- and multi-vortex. The Reynolds number and the absolute value pressure are the most important parameters which influence the existence and the number of these vortices, and the increase of the two parameters reduces the no vortex transition zone and causes bigger difference in the back-wall and side-wall vortex zones.

This paper examines free-surface vortices and the vorticity distribution with time-dependent evolution within a closed pump intake under five pressure conditions. The location and the strength of t...

Non-O157 Shiga toxin (

Tip clearance has a great effect on the flow and pressure fluctuation characteristics in a multiphase pump, especially at multiple operating points. The phase distribution and pressure fluctuation in tip clearance in a multiphase pump are revealed using the CFD (computational fluid dynamics) technology and high-speed photography methods. In this paper, the phase distribution, the gas-liquid two-phase velocity slip, and the pressure fluctuation intensity are comprehensively analyzed. Results show with the increase of the tip clearance, the multiphase pump pressurization performance is obviously deteriorated. In the meantime, the gas accumulation mainly occurs at the hub, the blade suction side (SS), and the tip clearance, and the maximum gas-liquid two-phase velocity difference is near the impeller streamwise of 0.4. In addition, the tip clearance improves the gas-liquid two-phase distribution in the pump, that is, the larger the tip clearance is, the more uniform the gas-liquid distribution becomes. Furthermore, the gas leads to the maximum pressure fluctuation intensity in the tip clearance which is closer to the tip leakage flow (TLF) outlet, and has a greater effect on the degree of flow separation in the tip clearance.

In this paper, the lattice Boltzmann method-large eddy simulation (LBM-LES) model was combined with the volume of fluid (VOF) method and used to simulate vortex flow in a typical pump intake. The strain rate tensor in the LES model is locally calculated utilizing nonequilibrium moments based on Chapman–Enskog expansion, and the bounce-back scheme is used for nonslip condition on the solid wall and VOF method for the free surface. The evolution of all kinds of cells on the free surface is based on the mass exchange in the VOF method, i.e., lattice Boltzmann-single phase (LB-SP) free surface model. The introduction of the external force terms is established through adding corresponding expressions on the right of the lattice Boltzmann equation (LBE), and by modifying the velocity. The predicted vortex flow patterns (core location and strength of the vortex) and velocity correlate with the experiments undertaken with the physical model. A comparison of the results demonstrates the feasibility and stability of the model and the numerical method in predicting vortex flows inside pump intakes. The model developed and presented in this paper provides a new analysis method of vortex flow patterns in pump intake from a mesoscopic perspective, enriches the relevant technologies, and makes corresponding contributions to further engineering applications.

The emotional change of a designer may lead to a different design decision and therefore affect the outcome of the design. This paper aims to explore factors that affect the emotions of designers during the design process. To be specific, through the method of multi-level screening, three experiments were performed, including the preliminary screening of 435 emotional words, the study on the relevance of designer emotions to the design process, and the semantic similarity analysis of emotional words, after which the set of 29 frequently-used words concerning designer emotions was constructed. Further, the factors and conditions that affect the emotional state of designers were summarized based on 1069 textual messages of emotional experience in a retrospective interview. The results show that the five major factors that cause the emotional change of designers are the state and capacity of designers themselves, interpersonal interaction and evaluation, external resources and environment, progress and content of the project, and the performance and innovation of tools, while 15 minor influencing factors were identified as well. Finally, four strategies were proposed to promote positive emotions during the design process from the perspective of design organizations and designers. By studying reasons for emotional state changes of the designer, the paper proposes a new perspective of self-understanding and self-examination for designers and the achievement of this research may offer valuable guidance for the practice of emotion management in design organization.

The era that focused on material aspects such as production and function has already passed. Modern design values spiritual aspects such as thoughts and feelings. Facing the increasingly lengthy and complex dynamic design links, how can we design for targeted experience is a challenge. In this context, this paper presents a method of user experience design from the perspective of scalability. To be specific, by teasing out and summarizing the present situation of scalable experience, the scalability of experience is identified. Based on different orientation, objects and characteristics, different dimensions are proposed for vertical and horizontal scalability of experience. Finally, the logic sequences are used to construct the explanatory models for different dimensions. This paper provides a new perspective and practical value for studies of user experience design.

The combined use of gastrointestinal hormones for treating metabolic diseases is gaining increasing attention. It was documented previously that co-administration of a cholecystokinin receptor-1 receptor (CCK-1R) agonist with a glucagon-like peptide-1 receptor (GLP-1R) agonist exerted improved effects on metabolic improvements in obese rodents. Here, we reported a series of novel GLP-1R/CCK-1R co-agonists constructed by linking the C-terminus of a GLP-1R agonist (native GLP-1 or Xenopus GLP-1) to the N-terminus of a CCK-1R selective agonist NN9056. The stability of co-agonists was further enhanced by introducing an albumin binding motif. In vitro functional assays revealed that the co-agonists retained full agonism potency on GLP-1R and CCK-1R. Particularly, 2a and 2c showed higher hypoglycemic and insulinotropic activities than NN9056 and semaglutide. The glucose-lowering durations and PK profiles of 2a and 2c were comparable to those of semaglutide. Desirably, in diet induced obesity (DIO) mice, 2a and 2c exhibited superior metabolic benefits to NN9056 and semaglutide in reducing food intake, inducing body weight loss, and regulating lipid metabolism. In short- and long-term studies in diabetic db/db mice, 2a and 2c showed enhanced effects on HbA1c, glucose tolerance, and pancreas function restoration compared with semaglutide. Importantly, no side effects, toxicities, or pancreatic inflammation were caused by 2a and 2c treatments. These preclinical studies suggest that the pharmacological effects of CCK-1 and GLP-1 pathways can be harnessed in a single fusion peptide, yielding a promising combination therapy strategy for treating metabolic disorders.

Diabetes is characterized by pancreas dysfunction and is commonly associated with obesity. Hypoglycemic agents capable of improving β-cell function and reducing body weight therefore are gaining increasing interest. Though glucagon-like peptide 1 receptor (GLP-1R)/cholecystokinin 2 receptor (CCK-2R) dual agonist ZP3022 potently increases β-cell mass and improves glycemic control in diabetic db/db mice, the in vivo half-life (

Velocity-skewed oscillatory sheet flow transport is studied by an approximate model for instantaneous sediment transport resulting from exponential profiles of sediment concentration and velocity over a mobile bed. The phase lag effect, and asymmetry in wave friction factor, oscillatory flow orbital amplitude, roughness height, bed shear stress and wave boundary layer thickness are modelled so that the net boundary layer stream of pure velocity-skewed oscillatory flow can be obtained. The proposed model is found consistent with the previous classical formulas, and qualitatively refines a series of exponents of velocity power function for the approximation of instantaneous sediment transport rate under different flow conditions. The sediment fluxes can be well predicted with accuracy as that of a two-phase numerical model. The net boundary layer stream and sediment transport rates are also well predicted, especially the negative net stream and rates with large phase residual. The phase residual is shown a useful but insufficient factor in the net sediment transport in pure velocity-skewed flows. In addition, the net boundary layer stream resulting from velocity-skewed wave boundary layer development difference between onshore and offshore flow durations is an essential factor as well.

Phosphorous (P) fertigation with high salinity water (HSW) drip irrigation would be an effective measure to relieve soil and water pollution caused by the excessive application of P fertilizer, and achieve synergistic saving of both limited fresh water and non-renewable P resources. However, the emitter clogging issues of drip fertigation systems seriously restricts the utilization of this technology. This study proposes an approach to reduce emitter clogging in HSW drip fertigation systems by choosing the appropriate type and concentration of P fertilizer. The effects of two new types of P fertilizers (ammonium polyphosphate, APP; urea phosphate, UP), and a traditional P fertilizer (monopotassium phosphate, MKP), were assessed at three fertilization concentrations (0, 0.15, and 0.30 g/L) on the clogging behavior of four types flat emitters. The results indicated that the application of MKP aggravated the clogging of emitters in comparison with non-fertilization. While the addition of two new types of P fertilizers (APP and UP) effectively alleviated emitters clogging (the irrigation uniformity of systems increased by 26.2%–74.6%) by inhibiting the formation of carbonate, although precipitation of phosphate, silicate, and quartz increased. Moreover, under the equal application amount of P fertilizer, UP and APP were more effective in relieving clogged when applied at a low-concentration with long-term running and high-concentration with short-term running mode. The results could pave a way for reducing the pollution in agricultural production and conserving freshwater and non-renewable P resources.

The two-dimensional (2D) axial-symmetric model is applied to investigate the transient cavitating flows in the reservoir-pipeline-valve (RPV) system. Firstly, the MacCormack scheme is used to solve the governing equations, and compared to the numerical results of the one-dimensional (1D) model, the 2D head peaks and time-dependent evolutions predicted by five-region turbulence model in the frozen form are in better agreement with the experimental results, and the comparisons show that the maximum head relative errors of the 2D model are generally smaller than those of the 1D model. Then, further numerical simulations are carried out to investigate the performances of different turbulence models incorporated in the 2D model. The comparisons between the numerical results and the experimental ones show the head curves of the two-region turbulence model are similar to those of the five-region turbulence model, which indicates that the transient cavitating flows are insensitive to the magnitude and distribution of the eddy viscosity in the core region. In addition, the sensitivity to the quasi-steady form and the frozen form of the five-region turbulence model is implemented in the 2D model; the numerical results predicted by the two forms both agree better with the experimental results, as the non-dimensional parameter P increases.

This study utilizes a qualitative approach and a two-phase numerical model to investigate net sediment transport caused by velocity skewness beneath oscillatory sheet flow and current. The qualitative approach is derived based on the pseudo-laminar approximation of boundary layer velocity and exponential approximation of concentration. The two-phase model can obtain well the instantaneous erosion depth, sediment flux, boundary layer thickness, and sediment transport rate. It can especially illustrate the difference between positive and negative flow stages caused by velocity skewness, which is considerably important in determining the net boundary layer flow and sediment transport direction. The two-phase model also explains the effect of sediment diameter and phase-lag to sediment transport by comparing the instantaneous-type formulas to better illustrate velocity skewness effect. In previous studies about sheet flow transport in pure velocity-skewed flows, net sediment transport is only attributed to the phase-lag effect. In the present study with the qualitative approach and two-phase model, phase-lag effect is shown important but not sufficient for the net sediment transport beneath pure velocity-skewed flow and current, while the asymmetric wave boundary layer development between positive and negative flow stages also contributes to the sediment transport.

It is more dangerous for the units sharing the same division pipeline system than those sharing individual system during the load rejection transient for a high water head pumped storage station. A new mathematical model for the load rejection transient in these two units sharing the same division pipeline was proposed using method of internal characteristic (MIC). The transient relationship between the geometric parameters and working parameters was established based on the dynamic equations of the hydraulic machinery. Meanwhile, the calculation of the load rejection transient was accomplished and compared with field experimental data from a pumped storage power station. The relative errors of the maximum rotational speed of the two units between the predicted results and the experimental data were −5.9% and −4.44%, respectively, and the relative errors of the maximum rising of hydraulic pressure were −6.7% and −6.98%, respectively. The results met with the design specification requirements, which indicated that the proposed new MIC could completely predict the load rejection transient in these two units with joint closing law of ball-valve and guide vane, and the corresponding calculated results were acceptable and reliable. The MIC is also applicable to the transient investigation of hydraulic systems with hydraulic machinery.

The Shan-Chen multiphase lattice Boltzmann model (LBM) coupled with Carnahan-Starling real-gas equation of state (C-S EOS)was proposed to simulate three-dimensional (3D) cavitation bubbles. Firstly, phase separation processes were predicted and the inter-phase large density ratio over 2×104was captured successfully. The liquid-vapor density ratio at lower temperature is larger. Secondly, bubble surface tensions were computed and decreased with temperature increasing. Thirdly, the evolution of creation and condensation of cavitation bubbles were obtained. The effectiveness and reliability of present method were verified by energy barrier theory. The influences of temperature, pressure difference and critical bubble radius on cavitation bubbles were analyzed systematically. Only when the bubble radius is larger than the critical value will the cavitation occur, otherwise, cavitation bubbles will dissipate due to condensation. According to the analyses of radius change against time and the variation ratio of bubble radius, critical radius is larger under lower temperature and smaller pressure difference condition, thus bigger seed bubbles are needed to invoke cavitation. Under higher temperature and larger pressure difference, smaller seed bubbles can invoke cavitation and the expanding velocity of cavitation bubbles are faster. The cavitation bubble evolution including formation, developing and collapse was captured successfully under various pressure conditions.

In order to improve the stability and the lifespan of rotating components in a canned motor of a centrifugal pump, a local hydraulic loss analysis has been performed based on detailed flow field analysis by Reynolds-averaged Navier–Stokes–based re-normalization group k-ε turbulence model simulation. An energy balance equation was applied to analyze the local hydraulic loss distribution. The stator flow channel in the motor was modeled as a porous medium, by utilizing the Ergun equation. Due to the complex structure and the velocity gradient in the complicated flow field, a strong circulation flow exists in the thrust bearing outer ring. Moreover, circumferentially asymmetric Taylor vortices in the vicinity of the hydrodynamic bearing and unsymmetrical Taylor vortices in the transitional region after the thrust bearing were predicted. Dean vortices in the distributary pipes are also captured. These complex vortices are accompanied with high dissipations. A strong increase in hydraulic losses are observed in the corresponding canned motor parts (x/x max = (0.03, 0.23), (0.87, 1)). Moreover, a strong increase in the radial force and the axial force are predicted in the relative parts of canned motor ( x/x max = (0.84, 0.97), x/x max = (0.24, 0.17), (0.84, 0.97), respectively).

The RNG k-ε turbulence model combined with cavitation model was used to simulate unsteady cavitating flows inside a double-suction centrifugal pump under different flow rate conditions based on hexahedral structured grid. The numerical external characteristic performances agree well with the experimental performances. The predicted results show that the turbulence kinetic energy and the turbulence dissipation rate inside the impeller at design flow rate are lower than those at other off-design flow rates, which are caused by various vortexes. Based on frequency-domain analyses in the volute casing, the blade passing frequency is the dominant one of the pressure fluctuations except the vicinity of volute tongue for all operating cases, and the dominant frequency near the volute tongue ranges from 0 to 0.5 times the blade passing frequency for other off-design points, while the blade passing one near the volute tongue is the dominant one of the pressure fluctuations at design point. The increase of flow rate reduces the pressure fluctuations amplitude. For cavitation cases, the blade loading of the middle streamline increases a bit during the initial stage, but, for serious cavitation, the blade loading near the blade inlet reduces to 0 and even negative values, and the serious cavitation bubbles block the blade channels, which results in a sharp drop in pump head. Under noncavitation condition, the predicted power related to the pressure in the impeller channels increases from the inlet to the exit, while, under different cavitation conditions at the design flow rate, these power-transformation distributions in the impeller channels show that these power conversions are affected by the available NPSHa and the corresponding work in leading regions of the blades increases increases gradually a bit, and then it increases sharply in the middle regions, but it decreases in the blade trailing regions and is greatly influenced by secondary flows.

A lattice Boltzmann model combined with curvilinear coordinate is proposed for lid-driven cavity three-dimensional (3D) flows. For particle velocity distribution, the particle collision process is performed in physical domain, and the particle streaming process is carried out in the corresponding computational domain, which is transferred from the physical domain using interpolation method. For the interpolation calculation, a second-order upwind interpolation method is adopted on internal lattice nodes in flow fields while a second-order central interpolation algorithm is employed at neighbor-boundary lattice nodes. Then the above-mentioned model and algorithms are used to numerically simulate the 3D flows in the lid-driven cavity at Reynolds numbers of 100, 400 and 1000 on non-uniform meshes. Various vortices on the x-y, y-z and x-z symmetrical planes are successfully predicted, and their changes in position with the Reynolds number increasing are obtained. The velocity profiles of u component along the vertical centerline and w component along the horizontal centerline are both in good agreement with the data in literature and the calculated results on uniform meshes. Besides, the velocity vector distributions on various cross sections in lid-driven cavity predicted on non-uniform meshes are compared with those simulated on uniform meshes and those in the literature. All the comparisons and validations show that the 3D lattice Boltzmann model and all the numerical algorithms on non-uniform meshes are accurate and reliable to predict effectively flow fields.

In this paper, the performances of linear and non-linear SGS models are compared by simulating a centrifugal pump impeller at both design load and quarter load. The mesh convergence is studied to choose the mesh with 2.05 million. At design load, the flow behaves well in both channels and the two models perform similarly. While at quarter load, the “two-channel” flow pattern occurs. Although this phenomenon is detected by both models, the peak value of the velocity profile moves towards the pressure side, showing opposite tendency to PIV. Comparing the two models under this condition, DNM shows significant priority over DSM due to the improved relation between the SGS stress, the rate-of-strain and the vorticity

The pressure fluctuation caused by unsteady flow in runner is one of the main reasons of vibration for a large Francis hydraulic turbine. It directly affects the steady operation of the hydraulic turbine unit. The existing research of the pressure fluctuation in hydraulic turbine mainly focuses on the unsteady flow in draft tube. Accurate distribution of pressure fluctuations inside a runner is not very clear. In this paper, the numerical method for predicting the pressure fluctuations in runner is investigated and the numerical simulation is performed for a large Francis hydraulic turbine. It is proved that the combination of shear-stress transport(SST) k-ω turbulence model and pressure-implicit with splitting of operators(PISO) algorithm could give more reliable prediction of pressure fluctuations in runner. The frequencies of pressure fluctuations in runner are affected by the flow in guide vane and the flow in draft tube. The first dominant frequency is significantly determined by the flow in draft tube, especially at part load condition. This frequency is approximately equal to one-third of the runner rotating frequency. The evident second dominant frequency is exactly equal to the guide vane passing frequency. The peak-to-peak amplitudes of pressure fluctuations in runner at small guide vane open angle are larger than that at large open angle at the same operating head. The amplitudes at points on blade pressure surface are generally greater than that on suction surface. The research results could be used to direct the hydraulic design and operation stability improvement of a large Francis hydraulic turbine.

This present paper proposes a two-dimensional lattice Boltzmann model coupled with a Large Eddy Simulation (LES) model and applies it to flows around a non-submerged groyne in a channel. The LES of shallow water equations is efficiently performed using the Lattice Boltzmann Method (LBM) and the turbulence can be taken into account in conjunction with the Smagorinsky Sub-Grid Stress (SGS) model. The bounce-back scheme of the non-equilibrium part of the distribution function is used to determine the unknown distribution functions at inflow boundary, the zero gradient of the distribution function is set normal to outflow boundary to obtain the unknown distribution functions here and the bounce-back scheme, which states that an incoming particle towards the boundary is bounced back into fluid, is applied to the solid wall to ensure non-slip boundary conditions. The initial flow field is defined firstly and then is used to calculate the local equilibrium distributions as initial conditions of the distribution functions. These coupled models successfully predict the flow characteristics, such as circulating flow, velocity and water depth distributions. The comparisons between the simulated results and the experimental data show that the model scheme has the capacity to solve the complex flows in shallow water with reasonable accuracy and reliability.

An improved large eddy simulation (LES) using a dynamic second-order subgrid stress (SGS) model has been developed for simulating dense particle-liquid two-phase turbulent flows. The governing equations of each phase are obtained from a microscopic point of view, using the kinetic theory of molecular gas. They are derived by multiplying the Boltzmann equation of each phase by property parameters and integrating over the velocity space. An inter-particle collision term is included in the governing equation of the particle phase. Assuming a Maxwellian distribution of the velocity for particle-phase, an inter-particle collision term is derived. A dynamic second-order SGS model is used in the LES to solve the governing equations. The coefficients of the second-order SGS model are obtained from the criteria of dimensional consistency and the invariants of strain-rate and rotation-rate tensors. During the simulation, the finite volume method (FVM) is used to discritize the governing equations with a staggered grid system. Continuity is conserved by the application of a mass-weighted method to the filtered governing equation. The SIMPLEC algorithm is used to solve the discretized governing equations. Body-fitted coordinates are used to simulate two-phase flows in complex geometries. This dynamic second-order SGS model has been successfully applied to simulate the dense particle-liquid two-phase turbulent flows in a centrifugal impeller and a duct. The simulated pressure and velocity distributions are in good agreement with experimental results.

Large eddy simulations were used to model the three-dimensional flows around a non-submerged spur dike. Based on the rigid lid assumption, all these vortex flows around the spur dike, which probably affected the whole flow field, were numerically simulated and analyzed. The largest circulating flow region caused by the spur dike behind it was weak, which would naturally lead to sedimentation for silt-laden twophase flows. Based on the Smagorinsky model, the finite volume method was used to discretize the NavierStokes equations, and the SIMPLEC algorithm was used to solve them. Meanwhile, these flows were investigated experimentally in a 0.5-m wide flume with a dike placed as a barrier. The computational results are in a fairly good agreement with the experimental data.

The location of two-stage air valve is usually installed in accordance with the experience and the related parameters are determined through repeated trial since the commercial software of water hammer calculation does not open the background. In this paper, the long-distance water pipeline was simulated using C++ programming to analyze suddenly pump stop event and genetic algorithm was adopted to optimize the parameters of air valve. Firstly, the boundary condition of the air valve and the theoretical calculation of the installation location had been established. Then, engineering examples under three conditions were programmed, which included (1) no protective measures after stopping the pump; (2) installation of the two-stage butterfly valve; (3) the installation of a two-stage butterfly valve and air valve joint protection. Finally, the optimal close process of the two-stage butterfly valve and the best intake and exhaust coefficient of the air valve were obtained by genetic algorithm. The results showed that: a two-stage valve installed can reduce the maximum positive and reverse speed control of pumps, while reasonable installation of air valve can effectively alleviate the negative phenomena. The location of the air valve was reliable on the basis of pressure judgment method(method two)or theoretical formula(method three).The maximum pressure in the pipeline was reduced with the increase of the area ratio of air valve μ when 0.1  μ  0.3 and was firstly decreased then increased with the increase of critical pressure Pcr. The results of after optimization and optimization of pre-computed are compared to indicate that the optimized parameters can be better for protection of water hammer, overcoming the deficiencies of commercial software.

Pumped storage plant is to develop energy conservation, improve the quality of power system operation important measures. Changing operating conditions of pump turbine unit including stable operation and the transition process is much more complex than conventional hydropower. Transient of hydraulic machine installations is one of the important decision-making process in pumped storage plant, thereby increasing the accuracy and applicability of the calculation of significance. Internal character analysis calculation of the hydraulic machine installation is a new theory of the transients, it can calculate without full-hydraulic machinery characteristic curves. This article describes the internal character analysis theory in the large pumped storage plant hydraulic calculation of the transients, and discusses some key issues to be addressed, and future direction of development.

Subgrid-scale (SGS) models for large-eddy simulation (LES) define the formalism of an effective eddy-viscosity model. The aim of this work is to quantify and compare different SGS models with experimental data. The first model investigated here is Smagorinsky model (SM), which is the earliest SGS model employed in LES, and given the Smagorinsky coefficient. The second model is dynamic model (DM), which has represented a great improvement in LES, and the coefficient is obtained dynamically. The third model is wall-adapting local eddy viscosity model (WALE), which based on the square of the velocity gradient tensor and has a proper near wall behavior. The last model investigated here is scale-dependent dynamic model (SDDM), which does not rely on the assumption that the model coefficient is scale invariant. The model is based on a second test-filtering operation which allows us to determine from the simulation how the coefficient varies with scale, but it was only validated in atmospheric boundary layer. The finite volume method is used to discretize the turbulence equations on a staggered grid system. The SMPLEC algorithm is used to solve the discrete turbulence equations. Body-fitted coordinates are used to simulate flows over complex geometry fields. The case here investigated are four SGS model of a three-dimension turbulence flows in 90°curved duct at Re = 40000. Finally, we find that the WALE model’s results agreed well with experimental results, indicating that the model and the calculated results are reliable. Meanwhile, the dynamic model also has an acceptable behavior to simulate turbulent flow, but its behavior is not as good as the WALE model, and better than Smagorinsky model. However, the SDDM has a bad performance to simulate turbulent flows of complex geometries. Therefore, the WALE model and dynamic model are applied in water turbine simulations.

Vibration caused by unsteady flow usually leads to a problem of stability in operation for large hydraulic turbines. This paper reports the recent investigation and analysis of vibration and pressure fluctuation problem on a prototype 700MW Francis turbine unit at the Three-Gorges Hydropower Plant in China. The site investigation were carried out for a wide load range of 200–600MW at the condition of water head 57–76m. Significant vibrations were observed on head cover when the turbine was operated at load of 540–542MW with water head 68.3m. To identify the causes, investigations were done by measuring oscillations of the guide-bearing, pressure fluctuations under the head cover and in the draft tube. A special vibration zone at frequency of 4.56fn (fn is the runner rotation frequency) was found by further spectrum analysis for the vibrations and pressure fluctuations, while this special zone was not found in other turbines in the same site with same configurations. On the other hand, the low-frequency vibrations caused by pressure oscillations of vortex rope in draft tube were also measured and analyzed.