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Synthetic Jet Actuator (SJA) works cyclically with the directionally transportation of fluid near the exit, and the paper presents the performance of a loudspeaker driven SJA in static flow field. Time-Resolved Particle Image Velocimetry (TR-PIV) system is used to measure the flow field characteristics near the SJA slot exit with input voltage changing, and the flow field snapshots obtained by TR-PIV are modality analyzed by Dynamic Mode Decomposition (DMD) method. The PIV experiments show that by varying input voltage at fixed oscillating frequency, the loudspeaker diaphragm vibration displacement is the parameter that affects the jet velocity and the performance of the SJA. The traveling vortex vanishes at high voltage due to the interaction between vortex structures and the synthetic main jet. In DMD method, the first three-order modes can characterize the main information of the original flow field with reverting the flow field snapshot sequence. It indicates that the DMD method is applicable in the SJA flow field research and the reduced order model can effectively simplify the analysis of flow field.

The scissors mode plays a crucial role in the study of the unitary Fermi gas. In this paper, we simulate the scissors mode by solving the hydrodynamic equations with appropriate initial conditions, and then extract the flow field of the gas. The flow fields in different regimes are found to be essentially different. The characteristic differences in the flow patterns between the superfluid and the normal viscous fluid are presented. Irrotational flow signals superfluidity, while rotational one indicates normal hydrodynamical behavior. These different characteristics can be visualized by the velocity portraits of the flow, which provide an intuitive way to discriminate the states of the Fermi gas.

In fluid mechanics research, understanding the motion behavior of particles in a flow field is crucial for comprehending particle transport, mixing, and deposition processes. However, due to the complex interactions between particles and fluids, a single method is insufficient to accurately describe the particle motion. To tackle this problem, this study proposes an unsupervised heterogeneous domain adaptation method based on fuzzy principles, called Particle Flow Motion Analysis (PMFA). First, the data originating from both the source and target domains are preprocessed and subjected to Principal Component Analysis (PCA). Then, fuzzy rules are introduced for feature selection. Finally, the Maximum Mean Discrepancy (MMD) and Canonical Correlation Analysis (CCA) algorithms are employed to optimize the distribution disparities and correlations between the heterogeneous domains. By constructing domain adaptation tasks and comparing with five other methods, the performance of the proposed method is evaluated. The results demonstrate that the PFMA achieves an average accuracy of 89.44%, an average recall rate of 85.87%, and an $F$1 value of 89.26% across four tasks, outperforming the other five comparative methods. The proposed method holds significant importance in gaining in-depth understanding of particle motion phenomena in fluids and revealing the underlying physical mechanisms and patterns.

To study the relation between cold-hot-water mixing ratio and outlet-water temperature of a mixer, the geometrical model of the mixer was built. On the basis of theoretical analysis, the outlet-water temperature with different mixing ratio of cold and hot water was simulated by FLUENT software. The results show that: flow field in mixer can be divided into recirculation zone and convection zone, in which there are different thermal resistances individually, and it result in the nonlinear relation in outlet average temperature and mixing ratio; there is a linear relation between outlet average velocity and mixing ratio, which accords to the mass conservation principle of non-compressible and continuous fluid flow.

The kinetic model for diffusion-controlled intermolecular reaction of homogenous polymer under steady shear was theoretically studied. The classic formalism and the concept of conformation ellipsoids were integrated to get a new equation, which directly correlates the rate constant with shear rate. It was found that the rate constant is not monotonic with shear rate. The scale of rate constant is N^-1.5 (N is the length of chains), which is in consistent with de Gennes's result.

Research on the flow field inside a turbo classifier is complicated though important. According to the stochastic trajectory model of particles in gas-solid two-phase flow, and adopting the PHOENICS code, numerical simulation is carried out on the flow field, including particle trajectory, in the inner cavity of a turbo classifier, using both straight and backward crooked elbow blades. Computation results show that when the backward crooked elbow blades are used, the mixed stream that passes through the two blades produces a vortex in the positive direction which counteracts the attached vortex in the opposite direction due to the high-speed turbo rotation, making the flow steadier, thus improving both the grade efficiency and precision of the turbo classifier. This research provides positive theoretical evidences for designing sub-micron particle classifiers with high efficiency and accuracy.

Measurement of temperature profiles of gas-solid two-phase flow at different heights in commercial-scale circulating fluidized bed (CFB) boilers was carried out. Experimental results showed that the thickness of thermal boundary layer was generally independent of the distance from the air distributor, except when close to the riser outlet. Through analysis of flow and combustion characteristics in the riser, it was found that the main reasons for the phenomena were: 1) the hydrodynamic boundary layer was thinner than the thermal layer and hardly changed along the CFB boiler height, and 2) both radial and axial mass and heat exchanges were strong in the CFB boiler. Numerical simulation of gas flow in the outlet zone confirmed that the distribution of the thermal boundary layer was dominated by the flow field characteristics.

Compared with circular, square and diamond piers, the N60 pier proposed in our previous study has been numerically proven to be effective in reducing tsunami force. The relatively stronger vortices behind the N60 pier are responsible for the not-small-enough tsunami force on the N60 pier. The asymmetry in shape makes the N60 pier fail to reduce flood force because flood propagates in the opposite direction of tsunami bore. A series of new type piers named $\mathrm{\text{N}}\alpha -\beta$ are proposed to further improve the anti-tsunami ability of the N60 by computational fluid dynamics (CFD) method among which the N60-60 pier is proven to be most effective in reducing tsunami force, and its tsunami force mitigation mechanism is analyzed numerically. Further, the physical experiments were conducted to validate the N60 pier and the new type pier N60-60. Results show that compared with circular, square and diamond piers, the N60 pier is indeed capable of reducing tsunami force, and compared with the N60 pier, the new type N60-60 pier is capable of further reducing tsunami force. The order of magnitudes of tsunami forces on piers is: N60-60 $<$ N60 $<$ circular $<$ diamond $<$ square.

In the present investigation, a three dimensional steady flow field model inside crystallizer system of a thin slab steel continuous caster is presented using real geometrical dimension starting from the inlet port of the nozzle. The nozzle flow was modeled considering the minimum casting defects. In addition, a new numerical model is developed for a thin slab casting mold. The velocity of the liquid from the inlet and outlet of the nozzle was considered as the boundary condition. The liquid flow field was computed with main concern on the velocities exiting the nozzle ports for the flow in the liquid pool. It was shown that the fluid pattern in the liquid pool has four main fluid rings including two fluid rings provided by the outer fluid coming from the bottom outlets into the liquid pool and two small fluid rings prepared by the fluid coming from the upper inlets into the liquid pool. The flow pattern agrees well with real measurements obtained by water model. The pool simulation shows asymmetries between two sides of the flow, mainly in the lower recirculation zone. The predictions of slag/liquid interface at the top side of the nozzle and its fluctuations show good agreement with the experimental results. The maximum upward wave flow occurred because of the liquid contact to the upper ports. Hence, a maximum upward flow wave was defined to prevent any unsteady state at the highest casting speed and lowest submergence depth.

Over the last decade, the focus on the use of computer tools to assess flows around submarines and guide their design has been considerably developed. In particular, with the emergence of parallel computational capabilities, RANS simulations of viscous flows have seen a greater role in predicting these flow fields. The shift to a much more CFD-based design and analysis approach leads to the ability to achieve better designs in the shortest time. This makes it possible to classify several ranges of designs as well as to provide an entire image of the flow field, which can lead to a better understanding of the flow field’s physics. The aim of this study consists of a 3D numerical simulation of the turbulent flow around a submarine without and with appendages to quantify the effect of each appendage on total drag and to study the interaction between the submarine hull and its appendages. The hydrodynamic turbulent flow behavior around the well-defined shape is described using the ANSYS CFX code to resolve the RANS governing equations. Good agreement is obtained from the validation of the numerical results confirming the efficiency of the method in terms of computational time and robustness. The numerical approach is adopted to predict the flow field and forces and moments acting on the underwater vehicle for different maneuvering cases and simulation results have been presented.

In this paper, we start from the fundamental of fluidic dynamics to set up a 1-D analytical model for a MEMS-based microfluidic device, and then we investigate the fluid flow in microchannel influenced by the acoustic field on the basis of acoustic streaming theory. Furthermore, finite element method in ANSYS is used to analyze the structural-fluid coupled field in microchannel actuated by ultrasonic vibration. The results of the acoustic pressure, frequency, velocity and driving force for the fluid flow in microchannel are presented in the end.

The flow through the throat-type energy-dissipators is calculated by using an axis-symmetrical K ~ ε turbulence model. The velocity field, the pressure field and the distributions of turbulent energy and its dissipation rate are acquired. The energy dissipation through the throat-type energy-dissipators can be seen in detail. The calculated pressure distribution is compared with the measured and in good agreement. The results are useful to understand deeply the flow characteristics of the throat-type energy-dissipators.

In order to overcome the shortcoming of small standoff distance of the submerged cavitating water jet, this paper proposes a new artificial submerged cavitating water jet nozzle. Fluent is used to perform the inner flow field simulation of the nozzle and several nozzles’ structural parameters are optimized through the total volume integral of vapor. The results demonstrate that the flow accelerates in the convergent section of the inner nozzle and expands in the diffuser. Additionally, cavitation takes place initially in the diffuser and small cylindrical section of the outer nozzle and the nozzles’ structural parameters have significant effects on cavitation. The cavitation quality is optimal when the outlet diameter of outer nozzle is 10 mm and the distance from the inner nozzle’s outlet to the outer nozzle’s convergent is 6 mm.

To study the flow field in saddle zone of a tubular pumping station, the three dimensional unsteady turbulent flow was numerically simulated with CFD software under different operational conditions. Some characteristics of flow field in saddle zone were obtained, and the results show that there is good agreement between experiment and simulation data and both of them illustrate the flow features of saddle zone under flow of 0.45Q_DES to 0.75Q_DES. With the decreasing of flow rate, the flow becomes more turbulent, and more vortex and backflow can be found with strong energy consumption, which is the main reason of saddle zone. Besides, the pressure fluctuation intensity with no obvious regularity of impeller inlet in saddle is much stronger than that of impeller inlet under designed flow rate.

In this paper, the effect of the dilation angle of base cavity on the aerodynamic force of the projectile is investigated numerically. The distributions of the flow field parameters and the drag coefficient of projectile with different dilation shape base cavity were obtained. Numerical results show that the shape of the base cavity has a remarkably effective on the aerodynamic drag of the projectile. Smaller dilation angle of the base cavity is benefit to reduce the aerodynamic drug of the projectile. With the dilation angle of the base cavity increasing, the aerodynamic drag of the projectile increasing too.

With the shape of the cooling channel being formed by the multi section of curved holes, the cooling water channel can be arbitrarily arranged according to the mold cavity, which can effectively reduce the temperature of the mold and improve the quality of the products. This paper describes the self guiding curved hole machining method based on the principle of electrochemical machining. In the analysis of curved hole machining process of cathode electrolyte flow field, designed the electrode structure and the liquid outlet form, used the RNG k-εmodel, a numerical simulation is performed on the stable machining of an electrolyte channel, then according to the simulation results, optimized the design of the electrode liquid outlet shape.

Results from experimental investigation and theoretical analysis of the relative velocity field inside a model centrifugal impeller were described and discussed. The experiments were performed in a specially designed perspex impeller of four logarithmic blades by employing a two dimensional particle image velocimeter system. Streamwise velocities were measured at three rotating speeds and three flow rates for each speed. Based on the experimental data, some important flow rules were formulated, theoretic explanation by means of vector analysis and potential flow theorem were also offered in the paper, which will contribute to improving pump performance.

A new pattern electromagnetic brake (EMBr) device is proposed in this paper, which is with two longitudinal vertical magnetic poles near the narrow face of mold, and the coverage range of magnetic field is from the meniscus to the impinging point of jet flow. For researching the braking effect of the new device, a three-dimensional mathematical model is established and used to solve the distribution of magnetic field and fluid flow in mold by software ANSYS and FLUENT. The results show that a substantially uniform distribution of the static magnetic field can be formed in molten steel where is covered by magnetic poles. With the new pattern EMBr device, the impact strength of jet flow from the submerge entry nozzle (SEN) to the narrow face of mold is greatly reduced, the flow velocity in mold is decreased obviously, the flow velocity and turbulent kinetic energy of free surface are all reduced and the vortex in lower recirculation is moved up. These are helpful to prevent some defects simultaneously such as steel leakage, entrapment of oxide inclusion engulfment of casting power at meniscus and bubbles on the solidified shell.