International Journal of Engineering Systems Modelling and Simulation (11 papers in press)
Modelling and simulation of an industrial flow between two moving permeable surfaces
by Jacques Hona
Abstract: Fluid distribution within a channel formed by two permeable surfaces that are accelerated in the streamwise direction is controlled using the Navier-Stokes equations. The mathematical model of the problem is reduced to solving a single, fourth-order, nonlinear ordinary differential equation by numerical integration. The analytical solution is derived for low values of the Reynolds number. The numerical results enable to characterize the influences of the permeation Reynolds number and the surface accelerating parameter on the flow streamlines, pressure gradients, velocity distribution, and wall shear stresses. It is found that positive accelerating parameters cause the backward flow which gives the existence of collision zones inside the channel. Boundary layers take place by increasing the fluid injection Reynolds number at a fixed positive accelerating parameter, and by increasing the suction Reynolds number at a fixed negative accelerating parameter. These boundary layers stop the oscillations of normal pressure gradients in the flow field.
Keywords: injection/suction-driven flow; Navier-Stokes equations; similarity method; numerical solutions; nonlinear boundary-value problem.
Numerical Simulation of Heat and Fluid Flow through Silicon Based Microchannel with Different Surface Roughness Elements
by Sasmita Bal, Purna Chandra Mishra, Ashok Kumar Satapathy
Abstract: A physical problem of laminar flow through a silicon based rectangular microchannel with designed surface roughness was solved numerically. Different shapes of the surface roughnesses such as: triangular, semicircular and trapezoidal were placed along the channel wall. The two dimensional problem was modeled and simulated in the FLUENTs computational fluid dynamics (FLUENT-CFD) environments. The working fluid taken was incompressible in nature hence the no-slip condition was assumed. The inlet condition was taken as constant velocity and at the outlet was considered as zero gauge pressure as boundary conditions. The total number of grids taken was 12444 for the computational domain. FLUENTs segregated solver as an implicit solver was used. The effects of different working fluids such as: water, ethanol refrigerant and engine-oil on heat transfer were investigated for the same value of roughness pitch and height. The simulation results revealed that the Nusselt number variation along the channel was more for engine-oil than that for ethanol and water. This might be due to the fact that Nusselt number is a function of Prandtl number and the Prandtl number is comparatively high for engine oil.
Keywords: Laminar flow; CFD; Microchannel; Surface roughness; Heat transfer.
A network traffic prediction method based on IFS algorithm optimized LSSVM
by Zhongda Tian, Shujiang Li
Abstract: How to predict network traffic accurately is an important issue in the network congestion control and network management. A network traffic prediction method based on improved free search algorithm optimized least squares support vector machines is proposed. Firstly, the Hurst exponent calculation shows that the network traffic time series has predictability, nonlinear and long-related characteristics, so least squares support vector machines is chosen as prediction model. Then an improved free search algorithm is introduced so that it can be applied into the parameters optimization of prediction model based on least squares support vector machines. Finally, the actual network traffic samples data of LAN and WAN are chosen as the simulation object, the simulation results show that the improved free search algorithm has faster convergence speed and better fitness value. Compared with other prediction methods, the proposed prediction method has better predictive effect and smaller predictive error. At the same time, the complexity of computation time shows that the proposed prediction method not only improves the prediction performance, but also does not increase the complexity of the algorithm.
Keywords: network traffic; prediction; least squares support vector machines; improved free search; optimization.
A NUMERICAL STUDY ON AERODYNAMIC WAKE FLOW CONTROL OVER AIRFOILS BY MICROJET ACTUATORS
by L. Prawin, Bruce Ralphin Rose
Abstract: The control of wake behind the aerodynamic surfaces like airfoils plays an important role for increasing the efficiency of control surfaces. Among the numerous techniques exist for controlling the separated flows, use of micro jet actuator is superior because of its ability to fit under various flow conditions. The present article involves the design of a micro jet actuator with ANSYS design modeller and it is analysed by computational flow analysis tools. The FLUENT analysis involves the use of moving wall boundary conditions for the bottom wall with dynamic mesh enabled mode. Initially, through the basic wind tunnel testing, the point of flow separation is observed for the given airfoil model. Then, the Micro jet actuator model has been implanted on the airfoil along the line of separated flow by utilizing the analysed data. The results are obtained at different time steps ranging from 1sec to 5 sec using CFX-Post processing tools. The airfoil with Micro jet implanted system has been analysed for various free stream flow velocities with time steps varying from 0 sec to 5 sec. Influence of Micro jets on the boundary flow control has revealed striking information over the airfoil model at each time steps and the results are presented. The outcome of this study can also be extended for other domains such as flow over high speed trains, wind turbines and automobile vehicles where the separated flow control is a complex subject.
Keywords: MJ actuator;Wake flow;Moving wall boundary condition;Transient flow analysis; ANSYS.
Implementation of 4D/BIM technology in the Iraqi construction industry
by Hussein Hamada, Ahmad Tarmizi, Zahrizan Zakaria, Ali Humada
Abstract: Building Information Modeling (BIM) is a new technique represented the transformation from traditional method to the method more modern in terms of dealing with digital data. 3D BIM with time schedule result to the 4D/BIM which represented by many of software such as Naviswork and Syncro. The aim of this study is to find out challenges of implementation 4D/BIM technology in the construction industry in Iraq. The data collection method for this research was through conducting a semi structure interview with civil engineer in al Najaf hospital project in Iraq, in addition to the an extensive literature review about the benefits, challenges and obstacles the implementation the 4D/BIM technique. The result proved that the construction industry in Iraq need to further support from the government through increasing awareness and financial support for construction companies.
Keywords: Building Information Modeling (BIM); 4D/BIM; al Najaf hospital project; Naviswork and Syncro; Iraq.
Numerical analysis of non-isothermal walls driven-gas flow
by Mohamed Hssikou, Jamal Baliti, Mohammed Alaoui
Abstract: The gas flow driven by non-isothermal walls effect is studied by both macroscopic and kinetic approaches. In this study, the behaviour of a rarefied and Maxwell gas flow induced by the thermal creep and stresses within a two-dimensional microcavity is investigated using the Direct Simulation Monte Carlo (DSMC) method and the regularised 13-moment equations solution. The upper and bottom walls of the microcavity are linearly heated from the cold and environmental temperature T_- to the hot one T_+. However, the left and right walls are kept at uniform and different temperatures T_- and T_+, respectively. The non-isothermal walls effect, at the vicinity of longitudinal walls, on the macroscopic gas proprieties is clarified for various values of the Knudsen number Kn, rarfaction degree. The agreement between DSMC and R13 results confirms the breakdowns of the classical Navier-Stokes and Fourier (NSF) theory for rarefied gas microflows.
Keywords: R13; DSMC; Thermal creep; microcavity; rarefied gas flow; NSF.
State Dependent Riccati Equation Sliding Mode Observer for Mathematical Dynamic Model of Chronic Myelogenous Leukemia
by Amin Sharafian, Zeinab Ebrahimi Fard
Abstract: In this paper we present a new alternative technique by combination of State Dependent Riccati equation (SDRE) and sliding mode to overcome the problem of state estimation of a natural system. Chronic Myelogenous Leukemia (CML) is one of the most common form of cancer treated with children. The huge number of immune cells impairs the ability of these cells and cause defectiveness of medulla ossium ability to make red blood cells and Platelets. Estimation of effector T-cells and the population of cancer cells in CML could reduce the number and expenses of medical tests for suffering patients. Adopting SDRE technique in line with Sliding mode observer could help us to achieve an optimum observer gain which prevent and reduce the observer system excitation and makes better estimation especially in natural systems such as CML. Moreover, SDRE technique brings certain nonlinear parts of the system to a seemingly linear structure and avoid linearization which reduce the accuracy of system. On the other hand, sliding mode applied to estimate unmodeled nonlinear dynamics, uncertainties and disturbances. Combination of these techniques make a better observer which benefit from both techniques features. Simulation results shows the effectiveness of the proposed observer for state estimation of the CML dynamical model.
Keywords: Chronic Myelogenous Leukemia; SDRE; Sliding Mode Observer; Optimal Observer.
Study on model of greenhouse gas N2O emission flux of rice field in cold region in growing season in water-saving irrigation mode
by Yu Lihong
Abstract: Under the condition of field experiment, 3 water management modes of control irrigation, intermittent irrigation and Flood irrigation were set, a static black box-gas chromatographic method was adopted for field in-situ observation on N2O emission flux of cold region rice field in the growing season, and two estimation models of N2O emission flux of rice in different water management modes in the growing season were established by using test data of 2014. All models were subjected to significance test, and the highly significant level (P<0.01) was met. The models were verified by using test data of 2015, the average prediction error of the models is 17.52%-27.46%, the adjusting correlation coefficient Radj2is within 0.412-0.643, and the model calculation value is relatively well accordant with practical test value. The test shows that: (1) optimal single factor models of N2O emission flux based on nitrate nitrogen concentration of soil are respectively: linear model of control irrigation mode, f= -2.202 N+13.595 (Radj2=0.394); logarithmic model of intermittent irrigation, f= -4.927Ln(N)+ 11.132 (Radj2=0.456); linear model of Flood irrigation, f=-3.099N+12.940 (Radj2=0.442). (2) Optimal single factor models of N2O emission flux based on soil temperature are respectively: logarithmic model of control irrigation mode, f=15.060Ln(T)-37.844 (Radj2=0.359); quadratic term model of intermittent irrigation, f= 0.034T 2-0.471T+1.072 (Radj2=0.462); linear model of Flood irrigation, f= 0.786T-12.563 (Radj2=0.374). (3) For interaction model of N2O emission flux based on temperature and nitrate nitrogen concentration of soil, the optimal model of control irrigation mode is: f=-0.249N 2+14.448Ln(T)-31.909, and the explanatory power is 54.0%; the optimal model of intermittent irrigation is: f= -3.405Ln(N) + 0.014T 2+3.767, and the explanatory power is 63.2%; the optimal model of Flood irrigation is f= -0.140N 2+0.053T 2-1.571N-1.650T+20.183, and the explanatory power is 60.2%. The interaction model can effectively describe the response features of rice field N2O emission flux to soil nitrate nitrogen and temperature coordinated variation better than any single factor model. The models of the study can be used for estimating N2O emission flux of rice field in the growing season in cold region of China.
Keywords: rice production in cold region; irrigation mode; N2O; model.
Mathematical Modeling and Simulation for Biogas Production from Organic Waste
by Liliana Delgadillo, Mauricio Hernandez, Maximiliano Machado
Abstract: This paper introduces the modelling, simulation of anaerobic digestion process for biogas production from organic waste. Insight on the relevant model parameters is obtained by performing a sensitivity analysis, followed by the estimation of the selected candidates using a Sequential Quadratic Programming algorithm. Calibration and validation of the model is based on experimental data obtained from a pilot-scaled plant, showing that the proposed model is able to correctly predict the Methane production dynamics from few key measurements.
Keywords: Acidogenesis; anaerobic digestion; methanogenesis; sensitivity analysis.
Research on Energy Consumption System of iron and steel enterprise with Bottleneck
by Demin Chen, Lu Biao, Chen Guang
Abstract: For improving the energy utilization efficiency of iron and steel enterprises, a systemic energy consumption analysis method was put forward in accordance with the index decomposition method of the e-p (IDM e-p) model. And this analysis method included that data collection of enterprise; the improvement of the IDM e-p (IIDM e-p) model; partial correlation analysis (PCA) of energy consumption influencing factors in bottleneck location; multiple linear regressions (MLR) modelling in bottleneck position. And then, this systemic analysis method was used in an iron and steel enterprise. The analysis of the model showed that blast temperature and blast volume were key parameters on coke ratio in bottleneck location. The coke ratio decreased by 0.48kg/t when the blast temperature was increased by 1% (2.15
Keywords: the IIDM e-p model; PCA; MLR modelling; Bottleneck location.
CFD modeling of Air Temperature Distribution inside Tunnel Greenhouse in Semi Arid Region
by Maher Dhahri, Sami Ameur, Hana Aouinet
Abstract: In the semi arid region of the southern Mediterranean especially the middle east of Tunisia, one of the main problems of climates is the large diurnal amplitude of temperature, with too low temperature during winter nights and too height temperature during summer day for successful plant growth and development the control of greenhouse environmental parameters is very important. In this work, a computational fluid dynamic software (CFX15.0) was used to study the micro-climate in a 6
Keywords: Greenhouse tunnel; natural ventilation; CFD; Climate heterogeneity;.