Local Flux Distribution Research Articles

Solar-thermal conversion performance of heterogeneous nanofluids

Nanofluids have excellent optical and thermal properties and show great potential for applications in direct absorption solar collectors (DASCs). However, due to the preparation process or force interaction, the non-uniform distribution of NP radii (r) and volume fraction (fv) in heterogeneous nanofluids may affect the solar-thermal conversion performance. In this work, we established a multiscale model based on the finite element method (FEM) coupled with the Monte Carlo (MC) method to investigate the solar-thermal conversion performance of heterogeneous nanofluids. Results show that the non-uniform distribution of r has little effect on the solar-thermal conversion performance due to the weak scattering and strong absorption properties of NPs in dilute nanofluids. The non-uniform distribution of fv has great effect on the local heating flux distribution in the heterogeneous nanofluid, which would affect the collector efficiency (ηcol) due to the different surface heat losses. And a superior ηcol can be achieved at a downward-gradient distribution of r and fv compared with uniform or upward-gradient distributions. This work develops an effective method to evaluate the solar-thermal conversion performance of heterogeneous nanofluids and provides a promising strategy by tuning the distribution of r and fv to enhance the solar collector performance.

Inverse Design of Local Solar Flux Distribution for a Solar Methanol Reforming Reactor Based on Shape Optimization

In this work, an inverse design method that couples the multi-physics model for a solar trough thermochemical reactor (SPTR) and shape optimization model is proposed to find out optimal solar flux distribution for maximizing overall reactor performance. The gradient-based segmentation method is applied to convert the continuous solar flux into step-like flux to guide the concentrator system design. Performance comparisons among uniform flux, linear decreasing flux, and the optimized non-linear flux are also conducted to discuss the reliability of SPTR performance improvement. The results show that the optimized non-linear solar flux can improve the methanol conversion, solar thermochemical conversion, and hydrogen yield of SPTR by 2.5, 3.3, and 2.4%, respectively, compared with the uniform flux. This is attributed to the fact that the optimized non-uniform flux distribution enhances the synergy between temperature and reaction fields, and achieves a better match between spatial solar flux supply and local energy demand by reactions. Also, it is shown that the optimized step-like flux, achieved by regressing the optimized non-linear flux, can perfectly maintain SPTR performance and is effective in boosting SPTR performance under different operating conditions.

Do ambient shear and thermal stratification impact wind turbine tip-vortex breakdown?

Modern wind turbines experience uneven inflow conditions across the rotor, due to the ambient flow’s shear and thermal stratification. Such conditions alter the shape and length of turbine wakes and thus impact the loads and power generation of downstream turbines. To this end, understanding the spatial evolution of the individual wakes under different atmospheric conditions is key to controlling and optimising turbine arrays. With this numerical study we aim to obtain a better understanding of the fundamental physics governing the near-wake dynamics of wind turbines under shear and thermal stability, by examining their tip-vortex breakup mechanisms. Our approach considers scale-resolving simulations of a single turbine wake under a linear shear profile as well as the application of harmonic tip perturbations to trigger flow instabilities. For the subsequent analysis we use the proper orthogonal decomposition (POD) method to extract coherent structures from the flow, and we also calculate mean kinetic energy fluxes to quantify each coherent structure’s contribution to wake recovery. The wake’s helical spiral is found to hinder wake recovery for all studied ambient flow conditions, whereas the mutual inductance instability has positive MKE flux leading to an enhanced wake recovery. Finally, the ambient shear has the largest impact on the local MKE flux with respect to downstream location by changing the shape of the curve and location of extrema, whereas thermal stratification has only a minimal impact on the magnitude of the near-wake local MKE flux distribution.

Remote sensing of methane plumes: instrument tradeoff analysis for detecting and quantifying local sources at global scale

Abstract. Methane (CH4) is the second most important anthropogenic greenhouse gas with a significant impact on radiative forcing, tropospheric air quality, and stratospheric water vapor. Remote sensing observations enable the detection and quantification of local methane emissions across large geographical areas, which is a critical step for understanding local flux distributions and subsequently prioritizing mitigation strategies. Obtaining methane column concentration measurements with low noise and minimal surface interference has direct consequences for accurately determining the location and emission rates of methane sources. The quality of retrieved column enhancements depends on the choices of the instrument and retrieval parameters. Here, we studied the changes in precision error and bias as a result of different spectral resolutions, instrument optical performance, and detector exposure times by using a realistic instrument noise model. In addition, we formally analyzed the impact of spectrally complex surface albedo features on retrievals using the iterative maximum a posteriori differential optical absorption spectroscopy (IMAP-DOAS) algorithm. We built an end-to-end modeling framework that can simulate observed radiances from reflected solar irradiance through a simulated CH4 plume over several natural and artificial surfaces. Our analysis shows that complex surface features can alias into retrieved methane abundances, explaining the existence of retrieval biases in current airborne methane observations. The impact can be mitigated with higher spectral resolution and a larger polynomial degree to approximate surface albedo variations. Using a spectral resolution of 1.5 nm, an exposure time of 20 ms, and a polynomial degree of 25, a retrieval precision error below 0.007 mole m−2 or 1.0 % of total atmospheric CH4 column can be achieved for high albedo cases, while minimizing the bias due to surface interference such that the noise is uncorrelated among various surfaces. At coarser spectral resolutions, it becomes increasingly harder to separate complex surface albedo features from atmospheric absorption features. Our modeling framework provides the basis for assessing tradeoffs for future remote sensing instruments and algorithmic designs. For instance, we find that improving the spectral resolution beyond 0.2 nm would actually decrease the retrieval precision, as detector readout noise will play an increasing role. Our work contributes towards building an enhanced monitoring system that can measure CH4 concentration fields to determine methane sources accurately and efficiently at scale.

Evaporation of a small water droplet sessile on inclined surfaces

A three-dimensional numerical model is developed to explore the evaporation of a small water droplet sessile on inclined surfaces. Important transport mechanisms, including evaporative cooling, heat transfer, vapor diffusion and natural convections in both liquid and gas domains are taken into account. The accuracy of the present model is first validated by comparing the total evaporation times and volume evolution curves obtained by the present model with those measured from experiments in the literature. The transport details and evaporation characteristics are then investigated. Under the influence of the combining effect of natural convection and evaporative cooling, the overall evaporation rate increases first as the inclination angle gets enlarged till ∼75°, and then decreases with further increase of the inclination angle. The flow field in the gas domain is converted from symmetry to asymmetry with the increase of the inclination angle, and the flow intensity near the droplet is also enhanced, which accelerates the evaporation. At the same time, the local evaporation flux distribution at gas-liquid interface changes from symmetry to asymmetry and the location of the lowest evaporation flux moves from the droplet apex to its waist (on the higher side of the droplet). The total evaporation times of droplets evaporating on vertical surfaces are shorter than those on horizontal surfaces by up to ∼9.38% when the substrate temperature is 40 °C higher than the ambient. The flow behavior inside the droplet is also discussed. With the increase of the inclination angle (0°∼180°), the flow pattern inside the droplet changes from double-vortex flow to single-vortex flow and to double-vortex flow again. The flow velocity magnitude is remarkably increased with the inclination angle increases from 0° to 90°

Investigation on structural and optical characteristics for an improved compound parabolic concentrator based on cylindrical absorber

In order to achieve the separation of absorber and reflector for compound parabolic concentrator (CPC) and solve effectively the drawback of resulting gap loss, an attempt to improve the structure and optical properties of CPC with cylindrical absorber is presented. Herein, a mathematical model of profile curve for the improved CPC is firstly established according to differential geometry. The structure of the improved CPC is more compact because of its saw-tooth, and it is beneficial to economize on the material with a reduced height of 24.1%. The ray path in practical application for improved CPC is verified via home-built experimental platform with laser generator. Furthermore, the mathematical relationships of optical efficiencies versus projected incident angles are revealed via numerical fitting. The optical efficiency curve for improved CPC is smoother and the non-uniformity of local flux distribution on absorber tube is mitigated, which predicts that the energy output of improved CPC is more stable. Compared with common CPC, the improved CPC provides an enhancement of absorbed total solar energy, which is increased by 8.3%, 4.8%, 7.4% and 2.9% in spring, summer, autumn and winter, respectively. The meaningful research results are beneficial to the structure design and performance enhancement of CPC.

Cold wall effects of control rod guide tubes and experimental flow channel walls

In rod bundle experiments, coarse flow housing walls are used to provide flow boundaries for the working fluid. In the PWR (Pressurized Water Reactor) reactor core, the guide tubes are needed to provide channels for control rods. The non-prototypical flow channel walls and guide tubes have similar cold wall effects on the thermal and hydraulic conditions of the surrounding flow channels. They might influence the local temperature, quality and mass flux distributions, which could have potential impacts on local mass and heat transfer characteristics. For example, when the flow resistance in the boiling hot channel increases due to steam generation, the adjacent cold channels around the guide tube can bypass the coolant and lead to the escalation of flow starvation in the steaming hot channel, which might ultimately lead to the early occurrence of a boiling crisis. In the rod bundle experiment, in order to ensure the representation of the CHF experiments, it is important to minimize the effects of the non-prototypical flow channel walls.In this paper, the wall effects of flow channel walls in a typical 5 × 5 rod bundle CHF test configuration have been minimized by optimizing the rod-to-wall gap (the gap between the outer rod wall and the channel inner wall design) through analytical analysis, CFD modeling and subchannel code calculation. This study concluded that the proper rod-to-wall gaps in the thermal field are often different from that in the hydraulic field. Therefore reasonable weight factors have been proposed to incorporate different impacts from these two fields. In order to determine proper design of rod-to-wall gap, the average temperature criterion, average mass flux criterion and maximum wall temperature criterion have been examined. Similarly, the cold wall effects of guide tube have been investigated using the theoretical model developed for the thermal field.

Impact of Punching Parameter Variations on Magnetic Properties of Nongrain-Oriented Electrical Steel

The efficiency and performance of an electrical machine depend on the magnetic properties of its magnetic core, i.e., the rotor and stator core made of stacked and processed electrical steel laminations. Especially a mechanical cutting, also known as punching or blanking, deteriorates the magnetic material properties next to the cutting line due to induced residual stress. The extent of the deterioration depends on the amount of induced stress, which is affected by the mechanical material properties and the process parameters used during punching. For this reason, in this paper, the effect of punching parameter variations on the magnetic properties of eight different nongrain-oriented electrical steels is investigated by using a single-sheet tester. The magnetic property deterioration is discussed based on the specific loss and the maximum field strength increase. In addition, the impact of punching parameter variations on the efficiency and the local flux and loss distribution of a permanent-magnet synchronous machine is shown based on a finite-element analysis. This allows one to tailor the punching parameters toward energy-loss minimization.

Computational fluid dynamic modeling of alternating tangential flow filtration for perfusion cell culture.

Alternating tangential flow (ATF) filtration has been successfully adopted as a low shear cell separation device in many perfusion‐based processes. The reverse flow per cycle is used to minimize fouling compared with tangential flow filtration. Currently, modeling of the ATF system is based on empirically derived formulas, leading to oversimplification of model parameters. In this study, an experimentally validated porous computational fluid dynamic (CFD) model was used to predict localized fluid behavior and pressure profiles in the ATF membrane for both water and supernatant solutions. The results provided numerical evidence of Starling flow phenomena that has been theorized but not previously proven for the current operating parameters. Additionally, feed cross flow velocity was shown to significantly impact the localized flux distribution; higher feed cross flow rates lead to an increased localized permeate flux as well as irreversible and reversible fouling resistance. Further, the small average permeate flux values of 2 L·m−2·h−1 traditionally used in perfusion bioreactor membranes lead to approximately 50% of the membrane length utilized for permeate flow during each pressure and exhaust phase, leading to a full membrane utilization during one ATF cycle. Our preliminary CFD results demonstrate that local flux and resistance distribution further elucidate the dynamics of ATF membrane fouling in a perfusion‐based system.

From Chaos to Order: Evaporative Assembly and Collective Behavior in Drying Liquid Crystal Droplets.

The emergence of dynamic assembly and collective motion in living systems are marvels of nature that suggest universal principles for governing self-organization. By drying a drop of surfactant-stabilized liquid crystal emulsions, we present a simple form of evaporative assembly and collective motion in colloidal droplets. Driven by local evaporation flux distribution and capillary force, the dynamic mode in these swimming liquid crystal droplets highly depends on their intrinsic configurations, exhibiting a macroscopic transition from chaotic to well-organized. The combination of collective behavior, speed distribution, interparticle interaction, formation of topological defects and dislocations in a swarm of hexagonal ordered liquid crystal droplets produced a myriad of dynamical states, which suggest a means of mimicking the nonequilibrium state of living matter with controlled properties.

Non-uniform distribution of adsorptive fouling along hollow fiber membrane: Characterization and quantification

Abstract Non-uniform distribution of local flux along the hollow fiber (HF) membrane length poses a high risk of partially overloaded flux to exacerbate membrane fouling. In-depth analysis of its effect on fouling is critical to the design of membrane geometry (e.g. fiber length, inner and outer diameters). This study focused on HF membrane adsorptive fouling by soluble organic substances under the influence of local flux distribution. The non-uniform distribution of adsorbed foulant was experimentally observed via fluorescence and contact angle measurements. An HF-Thomas model was then developed to describe the dynamic adsorption process (free/adsorbed concentration as a function of time), by incorporating Langmuir and Linear adsorption kinetics into the hydrodynamics of the HF membrane lumen. The model fitting was found to be effective in determining the HF membrane adsorption parameters (equilibrium and rate constants) of typical polysaccharide, protein, and humic acid model compounds. Extended simulation was conducted using the HF-Thomas model to explore the impacts of local flux distribution on foulant mass transfer and adsorptive fouling distribution under different scenarios of membrane geometry. The non-uniformity of flux and adsorption was found to be markedly amplified by a comprehensive dimensionless factor, λl (which derives from fiber length, inner and outer diameters, and intrinsic filtration resistance). Therefore, λl may qualify as a critical parameter for HF membrane design. According to the results of this study, λl

Time-dependent density functional theory for fluid diffusion in graphene oxide membranes/graphene membranes

We have used a time-dependent density functional theory (TDDFT) to study molecular transport in graphene oxide membranes (GOMs)/graphene membranes (GMs) with offset angle disordering. We have demonstrated that slight disordering of the GOMs/GMs is favorable to molecular transport, and may affect the diffusion selectivity. This phenomenon can be further understood by considering microscopic properties such as the local flux distribution. The maximum of the local flux is located at the edge of the graphene sheet, which could explain previous simulation findings. Additionally, the time-dependent properties have also been examined. A large offset angle in the GOM/GMs seems to be a favorable factor in the initial stage of the transport, but becomes unfavorable when the transport reaches a stable state.

Optical analysis of a novel collector design for a solar concentrated thermoelectric generator

This paper proposes a novel design for a solar concentrated collector for thermoelectric power generator (SCTEG), with optimum power output per unit length of collector. This collector consists of a parabolic trough concentrator (PTC) and a receiver mounted with two thermoelectric generators (TEGs) along the aperture of the concentrator. In addition to assessment of the conventional design parameters, this study investigates the effects of two new geometrical parameters on the optical performance of SCTEGs. These parameters are the vertex angle between the inner surfaces of the TEGs, and the focus offset, which is the displacement of the vertices of the TEGs above or below the focal point of the concentrator. A geometric model, which develops the basis of a ray-tracing technique for performing the optical analysis, is also described. Simulations performed for a set of design parameters showed that both parameters affected not only the optical efficiency but also the local flux distribution (LFD) on the surface of the TEGs. Iso-optical efficiency contours and numbers of LFDs were plotted, taking different values of these parameters to determine optical efficiencies. A flat-plate receiver configuration showed 85.2% optical efficiency but with a single high peak in LFD at the centre, which was undesirable. A slight alteration in vertex angle and focus offset resulted in same optical efficiency but improved LFD. The highest optical efficiency determined was 93.61% for the wide-receiver configuration. A thermodynamic analysis of the SCTEG design is also presented. This research work will assist in the development of more efficient SCTEGs.

Improvement in the simulation of detector readings using a high fidelity local flux reconstruction-based method

Even with current computing capabilities, detailed full core three-dimensional (3-D) transport calculations are still not practical. However, if we are satisfied with knowing only the average values of spatial flux distributions, the 3-D diffusion solution will constitute the final solution. On the other hand, in reactor design and safety analysis, direct information about the local flux distribution for the heterogeneous assemblies is required to assess the design and determine the safety margins. For this reason, after having solved the full-reactor-core problem, we have to look into the possibilities of recovering in a second step the information on local properties of single heterogeneous assemblies. In particular, the detector readings at detector locations are derived using these global homogenized parameters by applying appropriate numerical methods such as advanced interpolations. In this paper, we propose a method based on flux reconstruction to calculate the simulated detector readings in three-dimensions with high fidelity. Data from detector readings are very important in ensuring optimal reactor operations as well as in detecting any deviations from normal operations. Thus, calculating the detector readings with high fidelity will allow improvements to operating and safety margins. To validate this method, comparisons between detector reading simulation results and measurements from an operating CANDU reactor will be conducted and results will be presented.

Computational Studies for the Design Parameters of Hollow Fibre Membrane Modules

In this paper, several design features of Hollow Fibre Membrane Modules have been studied using Computational Fluid Dynamics (CFD). The features studied included the combined effects of packing density, fibre length, fibre inner diameter, as well as the potting thickness, so as to analyse the corresponding changes to the local flux distribution and permeate output flowrate. Under different feed pressures, simulation results showed that the decrease in feed pressure along the membrane fibre was greatly affected by both the fibre length and packing density. In general, fibres packed at 0.5 packing density (i.e. 50% of the total space within the module is occupied by hollow fibres) had the highest permeate flow rate, and the optimum packing densities of longer fibres (Length≥1m) were lesser than those of shorter fibres. The increase in inner diameter led to a proportional reduction in the permeate pressure, while improving the overall Transmembrane Pressure (TMP) and permeate flowrate. The inner diameter required for optimum output flowrate was dependent on the length of fibre used, in which longer fibres used required a larger inner diameter to ensure optimum output flowrate. Finally, reduction in permeate flowrate caused by potting thickness was found to be proportional to the permeate flowrate at the outlet of the hollow fibre.

Experimental investigation of interfacial energy transport in an evaporating sessile droplet for evaporative cooling applications.

In this paper we experimentally examine evaporation flux distributions and modes of interfacial energy transport for continuously fed evaporating spherical sessile water droplets in a regime that is relevant for applications, particularly for evaporative cooling systems. The contribution of the thermal conduction through the vapor phase was found to be insignificant compared to the thermal conduction through the liquid phase for the conditions we investigated. The local evaporation flux distributions associated with thermal conduction were found to vary along the surface of the droplet. Thermal conduction provided a majority of the energy required for evaporation but did not account for all of the energy transport, contributing 64±3%,77±3%, and 77±4% of the energy required for the three cases we examined. Based on the temperature profiles measured along the interface we found that thermocapillary flow was predicted to occur in our experiments, and two convection cells were consistent with the temperature distributions for higher substrate temperatures while a single convection cell was consistent with the temperature distributions for a lower substrate temperature.

Study of the footprints of short-term variation in XCO<sub>2</sub> observed by TCCON sites using NIES and FLEXPART atmospheric transport models

Abstract. The Total Carbon Column Observing Network (TCCON) is a network of ground-based Fourier transform spectrometers (FTSs) that record near-infrared (NIR) spectra of the sun. From these spectra, accurate and precise observations of CO2 column-averaged dry-air mole fractions (denoted XCO2) are retrieved. TCCON FTS observations have previously been used to validate satellite estimations of XCO2; however, our knowledge of the short-term spatial and temporal variations in XCO2 surrounding the TCCON sites is limited. In this work, we use the National Institute for Environmental Studies (NIES) Eulerian three-dimensional transport model and the FLEXPART (FLEXible PARTicle dispersion model) Lagrangian particle dispersion model (LPDM) to determine the footprints of short-term variations in XCO2 observed by operational, past, future and possible TCCON sites. We propose a footprint-based method for the collocation of satellite and TCCON XCO2 observations and estimate the performance of the method using the NIES model and five GOSAT (Greenhouse Gases Observing Satellite) XCO2 product data sets. Comparison of the proposed approach with a standard geographic method shows a higher number of collocation points and an average bias reduction up to 0.15 ppm for a subset of 16 stations for the period from January 2010 to January 2014. Case studies of the Darwin and Reunion Island sites reveal that when the footprint area is rather curved, non-uniform and significantly different from a geographical rectangular area, the differences between these approaches are more noticeable. This emphasises that the collocation is sensitive to local meteorological conditions and flux distributions.

Simulation of Lithium-Ion Conduction and Deposition with Heterogeneous Porous Structure of Electrode Layers and Separators

Recently, innovative design of electrode structure on the basis of kinetics and transport phenomena of ion is needed in order to increase the high-rate performance. Especially, its local ion flux distribution relates ununiformed reaction distribution and local Li metal deposition. So, the relationship between heterogeneous porous structure and its mass transport and reaction phenomena has to be known well to increase cell performance and durability. In our previous study, we focused on the actual heterogeneous structure and the Li ion and electron conductivity was evaluated by the effective conductive path with the actual reconstruction electrode structure of LiCoO2 cathode and graphite anode [1], [2]. Furthermore, the effect of volume expansion of charge-discharge state was evaluated by using simulation with structure change based on the actual porous electrode structure, and the relationship between structural change and battery performance was considered. In this study, Li deposition phenomena was modeled and combined to our previous simulation. And, the effect of porous separator structure on its phenomena was examined. Firstly, actual separator structure was reconstructed by focused-ion beam scanning electron microscopy (FIB-SEM: Helios NanoLab 600, FEI). In this study, Cryo-FIB-SEM with the function of frozen-cutting was used to prevent polymer material from melting by beam damage. The slice pitch was 20 nm in 200 slices. The validity of this structure was checked by comparing pore size distribution. Furthermore, in order to compare between the property of actual structure and theoretical physical limiting, various simulated structure were made by simulation, such as biaxial stretching structure, fibrous structure and foam structure. In simulation structure, the resolution is 0.1 mm/mesh, the porosity is 0.5, the thickness is 20 mm, and the size is (50 mm)2. Figure 1 shows reconstructed and simulated structure, Li+ flux distribution, standardized statistics of local Li+ flux and relative conductivity. In this figure, it was found that Li flux distribution of actual separator was not uniform. Comparing actual structure and foam structure, the relative conductivity of actual separator which was defined by the ratio between porosity and tortuosity can be increased 1.7 times, and the local flux can be uniformed with optimal structure. With these structures, the reaction and mass transfer in these reconstructed electrode structure and simulated separator structure were simulated by multi-block method [3] which is the method of coarse graining to keep the information of heterogeneous structure. Li concentration and potential distribution in active material (AM) and electrolyte (EL) were calculated with Butler-Volmer equation as the boundary condition of the interface between AM and EL. In addition, Li metal deposition reaction model and structural change effect were included our previous simulation. It was assumed that temperature is constant and that the formation of SEI is ignored. Figure 2 shows the example of Li metal deposition distribution in separator. Moreover, the relationship between porous structure of separator and deposition structure was examined.

A Study on the Optimal Position for the Secondary Neutron Source in Pressurized Water Reactors

Abstract This paper presents a new and efficient scheme to determine the optimal neutron source position in a model near-equilibrium pressurized water reactor, which is based on the OPR1000 Hanul Unit 3 Cycle 7 configuration. The proposed scheme particularly assigns importance of source positions according to the local adjoint flux distribution. In this research, detailed pin-by-pin reactor adjoint fluxes are determined by using the Monte Carlo KENO-VI code from solutions of the reactor homogeneous critical adjoint transport equations. The adjoint fluxes at each allowable source position are subsequently ranked to yield four candidate positions with the four highest adjoint fluxes. The study next simulates ex-core detector responses using the Monte Carlo MAVRIC code by assuming a neutron source is installed in one of the four candidate positions. The calculation is repeated for all positions. These detector responses are later converted into an inverse count rate ratio curve for each candidate source position. The study confirms that the optimal source position is the one with very high adjoint fluxes and detector responses, which is interestingly the original source position in the OPR1000 core, as it yields an inverse count rate ratio curve closest to the traditional 1/M line. The current work also clearly demonstrates that the proposed adjoint flux-based approach can be used to efficiently determine the optimal geometry for a neutron source and a detector in a modern pressurized water reactor core.

Modeling of filtration characteristics during submerged hollow fiber membrane microfiltration of yeast suspension under aeration condition

A modeling of filtration characteristics during the submerged hollow fiber membrane microfiltration of yeast suspension under aeration condition was developed on the basis of hydrodynamic mathematical equations that describe the local flux distribution, particle deposition and gas–liquid two-phase flow. The effects of average operating flux, fiber length, inner diameter and aeration rate on the distributions of local flux and filtration resistance were investigated using the developed model. The model was validated using the literature data. The simulated results showed that the asymmetry of initial local flux distribution was intensified with the increase of aeration rate. The local fluxes along the fiber experienced the self-adjustment and reconstruction due to the changes of filtration resistance as the filtration processed. Furthermore, the local flux distribution along the fiber with a short length and large fiber inner diameter at a high operating flux would tend to become relatively uniform at the initial period of filtration.