The characteristic approximation is used to handle the convection part along the direc - tion of fluid namely characteristic direction to ensure the high stability of the method in approximating the sharp fronts and reduce the numerical diffusion ; the mixed finite element spatial approximation is employed to deal with diffusion part and approximate the scalar unknown and the adjoint vector function optimally and simultaneously ; in order to preserve the integral conservation of the method , we introduce the modified characteristic method 该方法对方程的对流部分沿流体流动的方向即特征方向离散以保证格式在流动的锋线前沿逼近的高稳定性,消除数值弥散现象;对方程的扩散部分采用最低次混合有限元方法离散、同时以高精度逼近未知函数及未知函数的梯度;为保证方法的整体守恒性,在格式中引入修正项
In chapter one , we propose a new mixed method called characteristics mixed finite element method for a convection - dominated diffusion problems with small parameter e : we handle the convection part whth backward difference scheme along the characteristics , obtain much smaller time - trunction errors and avoid numerical dispersion on the front of the peak curve of the flow : we use a lowest order mixed finite element method to deal with the diffusion part , so this scheme can approximate the unknow function and its following vector with high accuracy at the same time 第一章中我们对小参数对流占优扩散问题提出了新的数值方法? ?特征混合有限元方法,即对方程的对流部分采用沿特征线的后退差分格式求解,以保证较小的截断误差限并避免了在流动的锋线前沿数值弥散现象的出现;对流动的扩散部分采用最低次混合元方法求解,以保证格式对未知函数及伴随向量的同时高精度逼近。由于该方法中检验函数可取分片常数,此格式在某种意义上具有局部守恒性质。
对流: convection; convection curre ...部分: part; section; portion非载流部分: non-current carry part; non-current carrying part回流部分: refluxing portion数据流部分: gif data stream通流部分: flow passage无电流部分: currentless part载流部分: conductive part; conductivepart; current carrying part; current-carrying part直流部分: direct component肺内分流部分: intrapulmonary shunt fraction蒸汽通流部分: steam path部分对流: semiconvection辐射炉(无对流加热部分): all-radiant furnace对流: [物理学][气象学] convection; convection current◇对流定律 law of convection; 对流放电 [电子学] convective discharge; electric wind; static breeze; 对流活动 [气象学] convective activity; 对流加热器 convection heater; 对流加速度 convective acceleration; 对流冷却 [工业] convection cooling; 对流平衡 convective equilibrium; 对流气流 [气象学] convection [convective] current; 对流区域 convective region; 对流热交换 convective heat exchange; 对流散热器 convector (heated) radiator; 对流选矿法 countercurrent treatment; 对流云 [气象学] convective cloud; 对流运输 cross haul of traffic (相向运输)下流部门: downstream sector溢流部位: position overflow; position, overflow载流部份: current-carrying parts直流部份: d-c component固定电流部件: fixed current unit过流部件采用: lwb对流胞 对流元: convectivecell部分: (整体中的局部或个体) part; section; portion 部分禁止核试验条约 treaty on the partial halting of nuclear tests; 我们看问题, 不但要看到部分, 而且要看到全体。 in approaching a problem we should see the whole as well as the parts. 他完成了自己的那部分工作以后, 又去帮助别人。 after finishing his share of the work he went to help the others. 我们部分地改变了原计划。 we've altered the original plan to some extent魁北克文化交流部: ministère de la culture et des communications du québec电对流: electric convection对流, 逆流: contra flow