Simulation Of Flow Behavior Research Articles

Numerical simulation of flow behavior in a urea liquid external gear pump with immersed solid method

Numerical simulation of flow behavior in a urea liquid external gear pump with immersed solid method

Numerical simulation of flow behavior in basilar bifurcation computed tomography angiography.

In this study, a moving boundary deformation model based on four-dimensional computed tomography angiography (4D-CTA) with high temporal resolution is constructed, and blood flow dynamics of cerebral aneurysms are investigated by numerical simulation. A realistic moving boundary deformation model of a cerebral aneurysm was constructed based on 4D-CTA in each phase. Four hemodynamic factors (wall shear stress [WSS], wall shear stress divergence [WSSD], oscillatory shear index [OSI], and residual residence time [RRT]) were obtained from numerical simulations, and these factors were evaluated in basilar artery aneurysms. Comparison of the rigid body condition and the moving boundary condition investigating the relationship between wall displacement and hemodynamic factors clarified that the spatial-averaged WSS and maximum WSSD considering only the aneurysmal dome has a large difference between conditions during the peak systole, and there were also significant differences in OSI and RRT.

Benchmark simulation code for the thermal-hydraulics design tool of the accelerator-driven system: validation and benchmark simulation of flow behavior around the beam window

ABSTRACT A detailed computational fluid dynamics code named JAEA Utility Program for Interdisciplinary Thermal-hydraulics Engineering and Research (JUPITER) for the thermal-hydraulics around the beam window (BW) of accelerator-driven system (ADS) was used to confirm the validity of the thermal-hydraulics design tool based on the ANSYS Fluent. The Fluent uses the Reynolds-averaged Navier–Stokes (RANS) model and can quickly calculate the turbulent flow around the BW as a BW design tool. First, the results of JUPITER were compared with the experimental results using a mock-up BW system in water to confirm the validity of JUPITER. This study confirmed that the numerical results are in good agreement with the experimental results. Thus, JUPITER could be used as a benchmark code. A benchmark simulation for the Fluent calculation was also performed using validated JUPITER to demonstrate the applicability of JUPITER as an alternative for experiments. Therefore, the mean values around the BW agreed with each other (e.g. the mean velocity profile for the stream and horizontal directions). Therefore, results confirmed that JUPITER demonstrated a good performance in validating the thermal-hydraulics design tool as a fluid dynamics solver. Moreover, Fluent has sufficient accuracy as a thermal-hydraulics design tool for the ADS.

Multi-scale simulation of flow behavior and microstructure evolution for AA2219 alloy during multi-pass ring rolling process

The multi-scale simulation of flow behavior and microstructure evolution of 2219 aluminum alloy during ring rolling was conducted. A new forming technology with two-stage hot−warm ring rolling was proposed compared to conventional hot rolling. The results show that the distributions of temperature, strain and strain rate are inhomogeneous on the cross section. The grains of edge nodes are elongated resulting from the larger strain and the low-angle grain boundaries transform into high-angle grain boundaries resulting in the increased fraction of recrystallization in hot rolling. The elongated banded structures change to equiaxed grains during the solution treatment, indicating complete static recrystallization. The inhomogeneous distributions of the temperature and strain result in heterogeneous microstructure distribution. The rolling force and the geometry of the ring were analyzed with experiment. The tensile properties in all directions of the ring and its isotropy are significantly increased with the new technology, especially the elongation.

Quantifying flow and velocity distributions in open channels with varied roughness and slopes: a modelling approach

ABSTRACT Understanding flow and velocity distributions in open channels is important for designing various hydraulic structures. This study focuses on modeling the flow and velocity distributions along with different open channel roughness (steel and concrete) and slopes from 0.0–4.7%, using an ultrasonic flowmeter and 3D scanner. Comprehensive Kriging and Linear Regression Models were developed to simulate flow behavior, considering the effects of surface roughness and channel slope. The models utilized appropriate boundary conditions by varying the roughness values. The concrete channel had an average centreline flow and velocity of 0.21 m3/s and 0.64 m/s, respectively, while the average flow and velocity for the steel channel was 0.33 m3/s and 0.97 m/s, respectively. The model’s accuracy and reliability were assessed by Pearson correlation and standard error of the estimate (SEE). According to the Pearson correlation, there is a significant relationship between the slope and flow on steel and concrete, with an average r equal to 0.75. The standard error of the estimates between observed and measured velocity and flow were 0.164 and 0.001, respectively.

The study on the effect of hydrodynamic flow on the photocatalytic performance of photocatalytic reactors.

The scalability of photocatalytic reactor is the major challenge due to the inability of the light penetration when the laboratory scale reactors are ascended. It is well known that the characteristic length of photocatalytic reactor is one of the influential parameters determining the efficiency of light penetration and also affects the hydrodynamic fluid flow behaviour inside the reactor. This study visualizes hydrodynamic flow behaviour of three differently configured photocatalytic reactors through numerical simulation of the fluid mass transport inside the reactors. The three photocatalytic reactors are (1) concentric cylindrical glass tube micro-reactor (CGTR), (2) UV-LED strip photocatalytic reactor (STR) and (3) classical annular reactor (CAR) from our previous work. The simulations of flow behaviour confirmed that CGTR exhibited plug flow regime, STR exhibited arbitrary flow (in-between continuously stirred tank reactor and plug flow reactor) and CAR behaved like continuously stirred tank reactor. Also, interpretations of numerical modelling were validated through plotting experimental residence time distribution curve. Furthermore, the comparison of performance parameters revealed that the highest modified space time yield (STYmodified) 225s-1and highest modified photocatalytic space time yield (PSTYmodified) 9.375s-1/kW/m3 was obtained for plug flow reactor when compared to continuously stirred tank reactor (CAR) and arbitrary flow reactor (STR). The study confirms that decrease in characteristic length of photocatalytic reactor onsets plug flow regime, which has highest photocatalytic performance efficiency.

Simulation and experimental investigation of centrifugal-cast functionally graded aluminum-B4C composite

ABSTRACT The present work investigates the flow behavior simulation and experimental validation for Al 6061-10 wt% B4C functionally graded aluminium matrix composite (FGAMC) by varying rotational speeds in a horizontal centrifugal casting (HCC) mold. A three-dimensional computational fluid dynamics model considering particle transportation and solidification based on the multiphase volume of fluid was analyzed using Ansys Fluent software. Simulated Particle gradient formation was validated against experimental data of solidified Al/B4C FGAMC. Simulation and experimental results showed 6.06% and 8.11% thinner outer region for mold speed from 1200 to 1400 rpm respectively. On the contrary, a 27% and 37% broadened thickness was observed at the inner zone for the same. The simulation and experimentation are in good agreement, and results show the formation of B4C particles gradient from outer to inner zone of FGAMCs. In addition, the effect of centrifugal speed on solidification rate and particle distribution has been explored.

The Development of Tubular Photobioreactor for Microalgae Cultivation

In a tubular photobioreactor, microalgae cells obscure one another (Self-shading), leading to the microalgae at the bottom of the tube getting less light. The objective of this research was to design and develop Tubular Photobioreactor with 93.5 liters for microalgae cultivation. The experiments had two steps. The first step was designing the solar receiver by inserting the fin into each tube wall as follows: 12-34, 1-2-3-4, 1234, and 13-24. Then, FLUENT software was used to simulate flow behavior inside the tube by Computational Fluid Dynamics by observing the pressure drop, the amount of energy consumption, and the swirling velocity to select the best fin-type. The best fin-type with the growth rate equation is introduced in the next step to simulate the microalgae's growth and movement using the user-defined function technique. The comparison of a tubular photobioreactor is investigated between fin and without fin by observing biomass production. The results showed that algae's optimum inlet velocity is 0.15 meters per second with the tubes containing fin-type 13-24. When simulating the growth behavior of microalgae, results show that the tubes without fins had lower biomass content than the 13-24 fin-type, which were 0.675 and 0.806 grams per liter, respectively, because the 13-24 fin-type will make well microalgae distribution leading to increase the light distribution too. Tubular photobioreactor fins type 13-24 had more biomass production, up to 19.4 percent.

Multiscale fractures integrated equivalent porous media method for simulating flow and solute transport in fracture-matrix system

The fracture–matrix system, in which water is stored and transported, has a significant impact on the hydraulic behaviors of fractured geologic media (FGM). However, it is very challenging to accurately simulate flow behavior in FGM due to the difficulty of characterizing dual-permeability media, including multiscale fractures with high permeability and porous matrix with low permeability. In this study, a multiscale fracture integrated equivalent porous medium (MFEPM) method is proposed for simulating fluid flow and solute transport in a fracture–matrix system. The synthetic enhanced matrix (SEM) is compounded by integrating small-scale fractures into the porous medium, and the medium- and large-scale fractures are mapped to refined grids of the MFEPM to increase the characterization of the fracture geometry and orientation. Then, the equivalent hydraulic properties are calculated according to the properties of the fractures. Finally, a finite difference method (FDM) based on the MFEPM is used to simulate flow and solute transport in coupled multiscale fractures and rock matrix. The case study illustrates that compared with the traditional equivalent porous medium (EPM) method, the MFEPM manifests an efficient effect in the characterization of preferential flow; compared with the discrete fracture network (DFN) method, the MFEPM can characterize flow and solute transport in the SEM and represent mass interactions between the fractures and matrix. The results of the numerical case studies of flow and solute transport also show that the MFEPM method has a high computational accuracy and good reliability, while maintaining an appropriate computational burden.

Experimental analysis and numerical simulation of flow behavior of fresh steel fibre reinforced concrete in magnetic field

• A numerical method was developed to investigate flow behavior of steel fibre concrete. • Magnetic flux density, initial position of steel fibre and resistance of mortar affect orientation. • Fluidity along magnetic field direction decreases with increase of magnetic flux density. Fluidity is an important index to describe the performance of fresh concrete, which has a great influence on the transportation and casting process of concrete. By applying a magnetic field to steel fibre reinforced concrete, in which steel fibre can be oriented to improve flow performance and strength. In this paper, the mechanical model of steel fibre in magnetic field was established in EDEM, and the simulations of magnetic field orientation as well as slump of steel fibre concrete were carried out and compared with the experiment. The errors between numerical and experimental results are less than 5%, which confirms the validity of the model. The effects of magnetic flux density and duration on the orientation of steel fibre and the effect of orientation on flow of mortar were analyzed. It was found that the larger the magnetic flux density, the better orientation of steel fibre. And regardless of the magnitude of magnetic flux density, most steel fibres can be oriented in a relatively short time. Due to the effect of gravity, orientation of mortar in the bottom is more difficult than that in the upper. The magnetic flux density, the initial position of the steel fibre and the resistance to the steel fibre affect the final orientation. When the magnetic field direction is horizontal, the fluidity of mortar along the magnetic field direction decreases with the increase of magnetic flux density, while the fluidity along the vertical magnetic field direction increases. The vertical magnetic field has no obvious effect on the fluidity.

Experimental and Mechanistic Characterizations of Oil-Based Cement Slurry Flow Behavior Through Fractures in a Carbonate Reservoir

Abstract In this paper, techniques have been developed to experimentally and mechanistically describe the oil-based cement slurry (OBCS) flow through fractures in carbonate reservoirs when it is co-injected with a pad fluid. Experimentally, a three-dimensional (3D) physical model is used to simulate flow behavior within fractures in carbonate rocks by using the ultra-fine cement and class G cement with or without pad fluids. The injection pressures of an OBCS flow are measured and recorded as a function of time during the experiments at a constant flowrate, while effects of fracture width (i.e., 0.5 mm and 1.0 mm) and cement type (i.e., the class G cement and the ultra-fine cement) on injection pressure are examined and analyzed. Theoretically, the Navier–Stokes (NS) equations are modified and integrated to obtain the explicit velocity equations of visco-plastic materials in a planar fracture, and to further quantify the injection pressure of the slurry flow as a function of viscosity, flowing distance of the injected slurry, fracture width, and flowrate. It is found from the experimental measurements that the fracture width imposes a much larger impact on injection pressure along the fracture than other parameters. Once slurry is made in contact with water, its injection pressure not only increases rapidly with one or two orders of magnitude or even larger but also is changed from its linear to exponential relationship with time after a certain time. During the linear stage, the injection pressure of ultra-fine cement is smaller than that of the class G cement, while an opposite pattern is yielded during the exponential stage, i.e., the exponent of the injection pressure formula pertaining to the ultra-fine cement is found to be about 1.5 times larger than that of the class G cement. By incorporating the experimentally measured patterns of the slurry distribution within the fracture model, the newly developed mechanistic model has been validated by reproducing the experimental pressure measurements, allowing us to perform reliable characterization of the OBCS flow behavior in a fracture and then to efficiently and accurately predict and optimize its water-plugging performance.

Numerical Simulation of Flow Behaviour of PLA and PLA-Copper during Fused Deposition Modeling Process

Fused deposition modeling (FDM) has been developed to adapt more application with a wide variety of material used, especially metal filled PLA filament. However, choosing wrong PLA-based filaments’ process parameters is a popular situation that causes great product’s dimensional error. This research is focused on studying the difference in the input velocity parameters between PLA and PLA-copper filament. This paper presents a numerical nozzle model and use finite element analysis method to investigate the melted filament fluid behavior. Flow parameters such as pressure, melting temperature range and velocity were discussed in detail. Experiments were then carried to determine optimal printing velocity range of the two filaments. Results show that the filament input velocity has great influence on flow parameters as this velocity changes, the flow parameters change as well. Finally, based on the evaluation of dimensional accuracy of printed samples, the optimal input velocity for each type of filament has been found, which are 2 – 3.5 mm/s for PLA and under 5 mm/s for PLA-copper.

Mesh-free simulations of injection molding processes

In this paper, we introduce a mesh-free numerical framework using the finite pointset method for the modeling and simulation of injection molding processes. When compared to well-established mesh-based methods, which have been widely applied for these applications, our approach avoids the need for extensive preprocessing and enables accurate treatment of free surfaces and other associated phenomena. To accurately model the polymer injections, we consider a detailed material model, with temperature dependent viscosity and density, while also considering shear thinning behavior with a strain rate dependent viscosity. Our numerical investigations show that injection molding-specific problems such as the modeling of viscous flows and the fountain flow effect can be successfully implemented using our presented framework. For a thorough validation of our proposed model, we compare the simulated flow behavior with injection molding experiments, which are also performed in this work. The experimental setup considers the injection of a polymer melt into a spiral mold. The flow behavior is investigated experimentally at varying melt injection and wall temperature, with different threshold pressures. Our numerical simulations show a good comparison with these experimental results, both qualitatively and quantitatively. We also introduce a correction mechanism to ensure energy conservation, which has often been challenging in mesh-free approaches. This is the first time that the flow behavior in a mesh-free injection molding method has been experimentally validated and successfully applied to the simulation of an actual industrial vehicle component.

Discontinuous and continuous Galerkin methods for compressible single-phase and two-phase flow in fractured porous media

Accurate simulation of flow behaviors in fractured porous media is challenging. We present a discontinuous Galerkin (DG) approximation and continuous Galerkin (CG) approximation for compressible single- and two-phase flow in porous media with conducting (high permeable) and blocking (low permeable) fractures using a mixed-dimensional approach in which the fracture is described as a reduced-dimensional interface coupled with linear transmission conditions. The proposed DG/CG method was first verified with single-phase fractured flow benchmark cases and then applied to time-dependent single-phase flow cases. The simulated results demonstrate that the DG/CG method is capable of capturing the continuity as well as the jump in pressure between the two sides of the matrix-fracture interface. For the two-phase flow cases, we verify the DG/CG method with a reference case involving a complex fracture configuration. Subsequently, we analyze several cases to study two-phase flow through a single fracture and a discrete fracture network in two dimensions. Overall, the simulation results show that the developed DG/CG approach can reliably predict the flow behaviors for single- and two-phase flow in fractured porous media.

Influence of cross-sectional velocity profile on flow characteristics of arterial wall modeled as elastic and viscoelastic material.

In the present work, blood flow behavior in a single artery and in arterial network is studied using time domain based one-dimensional wave propagation model retaining the nonlinear convective force. 1-D Navier-Stokes equation is used to model the flow behavior of the blood, using three unknown parameters: flow rate (q), cross-sectional area of artery (A) and pressure (p) based formulation. Three different approximate velocity profile functions across the cross-section namely modified flat, parabolic and the one proposed by Bessems are used to calculate the nonlinear convective force and the frictional force. Two different constitutive models, linear elastic model and standard linear solid model (Zener model) are used to model the arterial wall mechanical behavior. The system of partial differential equations is discretized using finite element and Crank Nicolson methods in space and time domains, respectively. Based on the formulation, an in house finite element code is developed to simulate flow behavior in both a single artery as well as in arterial network consisting of 20 small and large size arteries. Simulations are performed by enforcing a flow rate at the inlet and Windkessel model at the outlet. The results for elastic arterial wall model are found to be in good agreement with the results available in the literature. The flow rate/pressure predictions using different velocity profile functions are found to be nearly the same, however the Bessems velocity profile predicts more closer to 3D results compared to modified flat and parabolic profiles. Whereas, significant difference is found in the results predicted using elastic and viscoelastic artery wall models.

Evaluation of transient pressure responses of a hydraulically fractured horizontal well in a tight reservoir with an arbitrary shape by considering stress-sensitive effect

In this study, a semianalytical technique has been developed to examine stress-sensitive effect on the transient pressure responses of a multiple-fractured horizontal well in an unconventional reservoir with an arbitrary-shape. Considering its arbitrary-shaped boundaries, the boundary element method is adopted to simulate flow behaviour by incorporating the permeability modulus (i.e., stress-sensitive effect) into the governing equation to describe the flow behaviour within the hydraulic fractures. To weaken the nonlinearity of such governing equations in a hydraulic fracture subsystem, a semianalytical approach is used to achieve consistent solutions with good accuracy. The convergence skin effect is introduced to represent the radial fluid-flow pattern in the hydraulic fractures near the horizontal wellbore. Not only can the stress-sensitive effects of hydraulic fractures be examined, but also the corresponding pressure responses together with pressure derivative curves are obtained. The mathematical formulations have been verified and then extended for field applications. The stress-sensitive effect of hydraulic fractures in a box-shaped reservoir with closed boundaries is found to be obvious during the intermediate- and late-time periods. Furthermore, the noticeable stress-sensitive effect in hydraulic fractures occurs earlier by taking the convergence-skin effect into account. A hydraulic fracture with a high permeability modulus is found to result in a positive stress-sensitive effect. Also, sensitivity analysis on pressure responses and their corresponding derivative curves have been performed with respect to the convergence skin effect, boundary shape, maximum distance, and minimum fracture conductivity.

Numerical Simulation of Flow Behavior in Basilar Bifurcation Aneurysms Based on 4-Dimensional Computed Tomography Angiography

Initiation, growth, and rupture of cerebral aneurysms are caused by hemodynamic factors. It is extensively accepted that the cerebral aneurysm wall is assumed to be rigid using computational fluid dynamics (CFD). Furthermore, fluid-structure interactions have been recently applied for simulation of an elastic cerebral aneurysm model. Herein, we examined cerebral aneurysm hemodynamics in a realistic moving boundary deformation model based on 4-dimensional computed tomographic angiography (4D-CTA) obtained by high time-resolution using numerical simulation. The aneurysm of the realistic moving deformation model based on 4D-CTA at each phase was constructed. The effect of small wall deformation on hemodynamic characteristics might be interested. So, four hemodynamic factors (wall shear stress, wall shear stress divergence, oscillatory shear index and residual residence time) were determined from the numerical simulation, and their behaviors were assessed in the basilar bifurcation aneurysm.

High-performance hybrid modeling chemical reactors using differential evolution based fuzzy inference system

Bubbly flow behavior simulation in two-phase chemical reactors such bubble column type reactors is widely employed for chemical industry purposes. The computational fluid dynamics (CFD) approach has been employed by engineers and researchers for modeling these types of chemical reactors. In spite of the CFD robustness for simulating transport phenomena and chemical reactions in these reactors, this approach has been known as expensive for modeling such turbulent complex flows. Artificial intelligence (AI) algorithm of the adaptive network-based fuzzy inference system (ANFIS) are largely understood and utilized for the CFD approach optimization. In this hybrid approach, the CFD findings are learned by AI algorithms like ANFIS to save computational time and expenses. Once the pattern of the CFD results have been captured by the AI model, this hybrid model can be then used for process simulation and optimization. As such, there is no need for further simulations of new conditions. The objective of this paper is to obviate the need for expensive CFD computations for two-phase flows in chemical reactors via coupling CFD data to an AI algorithm, i.e., differential evolution based fuzzy inference system (DEFIS). To do so, air velocity as the output and the values of the x, and y coordinates, water velocity, and time step as the inputs are inputted the AI model for learning the flow pattern. The effects of cross over as the DE parameter and also the number of inputs on the best intelligence are investigated. Indeed, DEFIS correlates the air velocity to the nodes coordinates, time, and liquid velocity and then after the CFD modeling could be replaced with the simple correlation. For the first time, a comparison is made between the ANFIS and the DEFIS performances in terms of the prediction capability of the gas (air) velocity. The results released that both ANFIS and DEFIS could accurately predict the CFD pattern. The prediction times of both methods were obtained to be equal. However, the learning time of the DEFIS was fourfold of ANFIS.

A steady-state EMMS drag model for fluidized beds

Mesoscale structures exist inherently in fluidized beds and hence should be taken into account in the constitutive modeling of the drag force. To account for mesoscale effects, previous efforts have been paid on extending the steady-state Energy-Minimization Multi-Scale (EMMS) model to the sub-grid level by introducing acceleration terms into the force balance equations. The EMMS drag models thereof were normally confined into specific flow regimes. In this work, the definition of the heterogeneity index was refined by incorporating the steady-state force balance between the drag and buoyed weight. A simple derivation thereof agrees well with the filtered drag model. Based on such analysis, we proposed a new drag model by solving the steady-state EMMS equations. As a preliminary validation, this new drag was found to allow successful CFD simulation of flow behavior of fluidized beds covering a broad range of flow regimes.

Numerical simulation of flow behavior in basilar bifurcation artery aneurysms based on 4D-CTA

Numerical simulation of flow behavior in basilar bifurcation artery aneurysms based on 4D-CTA