Finite Difference Model For Simulation Research Articles

An Improved 3D Finite Difference Model for Simulation of Double Shield TBM Tunnelling in Heavily Jointed Rock Masses: the DXL Tunnel Case

An Improved 3D Finite Difference Model for Simulation of Double Shield TBM Tunnelling in Heavily Jointed Rock Masses: the DXL Tunnel Case

Hybrid lattice Boltzmann finite difference model for simulation of phase change in a ternary fluid

In this paper, a hybrid lattice Boltzmann finite difference model based on the phase-field lattice Boltzmann and finite difference approaches is proposed to model phase-change phenomena in a ternary system. The system contains three immiscible incompressible fluids and the phase-change process happens at the interfaces of the fluids. Three distribution functions are used in the model; two of which are used to track the interfaces among three fluids and the other one is employed to recover the hydrodynamic properties (pressure and momentum). A sharp-interface energy equation is solved based on a finite difference approach and the net heat flux at the interface is considered as the driving force for the phase-change process. The proposed model is validated against available results and good agreement is found.

Evaluation of the Impact of the Ongoing Water Resource Management Plans on Nitrate Concentration in Gaza Coastal Aquifer Using Modeling Approach

Groundwater crisis in Gaza includes two major folds: shortage of water supply and contamination. The groundwater pollution by nitrates increased rapidly as a result of wastewater leakage, sewage sludge, animal manure and N-fertilizers. The aims of this study are to obtain the impacts of implementing the Gaza Emergency Technical Assistance Programme (GETAP) on the nitrate concentration in groundwater in Gaza Strip using modeling approach. A flow and transport model using a three dimensional, finite difference simulation model (VMODFLOW Pro.) was applied to simulate the Gaza coastal aquifer (GCA). The approach for selecting the management scenarios was carried out depending on the GETAP projects and focuses into the aquifer system during the next 24 years. It was estimated that work as usual scenario will raise the average nitrate concentration by 8.15 mg/l annually, while upgrade and maintain pipe work scenario will reduce the rising of average nitrate concentration by 4.51 mg/l annually. This means that the average nitrate concentration will increase by only 3.63 mg/l annually. Also, it was estimated that scenarios imported water from Israel, construction of short term low volume desalination plant (STLV), Construction of two regional desalination plant and Reuse of treated wastewater in addition to decrease N-fertilizer will annually increase the average nitrate concentration by only (4.67, 2.78, 3.87, 2.15) mg/l, respectively. The results show that applying all the scenarios together will decrease the average nitrate concentration by 2.44 mg/l annually. Regionally, the best scenario to solve the increasing of nitrate concentration problem is a combination of those scenarios. In domestic areas, the best scenarios is STLV and upgrading and maintaining pipe work. In Agriculture areas, the best scenario and the only one that has significant effect is the reuse of treated wastewater in addition to decrease N-fertilizer.

3D finite difference model for simulation of double shield TBM tunneling in squeezing grounds

One of the main concerns in using a shielded machine in deep rock tunnels is the possibility of the shield seizure in squeezing ground. To realistically evaluate the possibility of machine seizure in such grounds, the interaction between the rock mass and shield, lining and backfilling need to be understood. This paper will explain the background theories and the application of numerical analysis for 3D modeling of mechanized tunneling by using a double shield TBM in squeezing ground. The discussions will include the effects of advance rate during excavation cycle of a shielded TBM to observe the impact of tunneling rate on the possibility of machine jamming in the squeezing grounds. Simulation results at five reference points on the tunnel circumference along the tunnel or longitudinal displacement profile (LDP) as well as longitudinal contact force profiles (LFP) on both front and rear shields have been examined. Also, maximum thrust force required to overcome friction and drive TBM forward is calculated. This exercise allows for evaluation of the effects of various parameters on convergence and contact forces between the rock and shield, which in turn determines the required propel forces and can define the possibility of machine entrapment.

동적결합둥지형 모형에 의한 동해안 쓰나미 시뮬레이션

상세한 지진해일 범람 현상을 규명하기 위하여 수립된 전회의 동적결합 차분 모형(Choi et al.)이 1983년 동해중부지진에 의한 지진해일 연구를 위해 우리나라 동해안 전역에 적용되었다. 계산영역은 격자의 크기가 다른 몇 개의 둥지영역이 평행하거나 경사가 진 방향으로 연결되어 구성되어 있다. 제일 안쪽의 둥지 영역은 해안을 따라 순차적으로 16영역으로 구성되었으며, 격자간격은 약 30m이다. 천수방정식(선형과 비선형)이 적용된 수치 시뮬레이션은 둥지영역의 격자크기에 따라 직각 또는 구면좌표계가 채택되었으며, 평행 및 경사 접합이 제일 안쪽의 둥지형 모형에 적용되었다. 시뮬레이션에 의한 결과는 지진해일 사상에 대한 처오름 높이의 관측치와 잘 일치하였다. 지진해일고 분포곡선의 개선이 수치적으로 연구되었으며, 지진원으로부터 거리가 먼 경우에는 대수정규분포를 따르는 경향을 보인다. A dynamically-interfaced multi-grid finite difference model for simulation of tsunamis in the East Sea(Choi et al.) was established and further applied to produce detailed feature of coastal inundations along the whole eastern coast of Korea. The computational domain is composed of several sub-regions with different grid sizes connected in parallel of inclined directions with 16 innermost nested models. The innermost sub-region represents the coastal alignment reasonably well and has a grid size of about 30 meters. Numerical simulations have been performed in the framework of shallow-water equations(linear, as well as nonlinear) over the plane or spherical coordinate system, depending on the dimensions of the sub-region. Results of simulations show the general agreements with the observed data of run-up height for both tsunamis. The evolution of the distribution function of tsunami heights is studied numerically and it is shown that it tends to the log-normal curve for long distance from the source.

Simulation of Bioventing for Soil and Ground-Water Remediation

A three-dimensional finite difference model for simulation of bioventing is presented. The model incorporates three-phase (gas-water-organic) flow with equilibrium interphase mass transfer and dispersive transport of organic compounds, oxygen, and carbon dioxide. Growth of microorganisms, substrate and oxygen consumption, and carbon dioxide production due to microbial activity are included. Biodegradation limitations due to both substrate and oxygen availability are modeled using the dual Monod formulation. The model is applied to predict the fate of a spill of toluene in the vadose zone under natural conditions and with various configurations of air injection and vapor extraction wells. Configurations of wells are determined that maximize biodegradation and minimize both the amount of toluene withdrawn in extraction wells and the amount lost to the atmosphere.

Finite difference model for simulation of 3-dimensional PIM

Finite difference model for simulation of 3-dimensional PIM

Fat metabolism in three forms of experimental obesity; fatty acid turnover.

Fat metabolism in three forms of experimental obesity; fatty acid turnover.