CAJ | 학술논문

重构引入有限增量微积分过程的压力稳定质量守恒方程,以克服因流体不可压缩性引发的压力场空间分布虚假振荡现象.采用离散的弹性-粘性应力分裂技术以在缺失纯粘性项情况下保持动量方程弱形式中的椭圆项贡献.利用迎风流线方法离散粘弹性Phan-Thien-Tanner本构方程中的对流项,基于Crank-Nicolson隐式差分格式的迭代稳定分步算法求解质量、动量守恒方程和本构方程.用流函数法追踪和确定移动自由面,对等温低密度聚乙烯和线型低密度聚乙烯熔体的挤出胀大进行数值模拟,数值结果与相关文献和试验结果吻合得较好.
중구인입유한증량미적분과정적압력은정질량수항방정,이극복인류체불가압축성인발적압력장공간분포허가진탕현상.채용리산적탄성-점성응력분렬기술이재결실순점성항정황하보지동량방정약형식중적타원항공헌.이용영풍류선방법리산점탄성Phan-Thien-Tanner본구방정중적대류항,기우Crank-Nicolson은식차분격식적질대은정분보산법구해질량、동량수항방정화본구방정.용류함수법추종화학정이동자유면,대등온저밀도취을희화선형저밀도취을희용체적제출창대진행수치모의,수치결과여상관문헌화시험결과문합득교호.
With the introduction of the finite incremental calculus procedure a pressure stabilized mass conservation equation is reconstructed to overcome spurious oscillations of resulting pressure spatial distribution due to incompressibility of fluids. The discrete elastic viscous stress splitting method is used to retain an elliptic contribution in the weak form of the momentum equation in the absence of a purely viscous contribution or as the viscous contribution is negligible in comparison with the viscoelastic contribution. Inconsistent streamline upwinding method is employed to spatially discretize the constitutive equation of the Phan-Thien-Tanner viscoelastic constitutive model. The mass, momentum and constitutive equations are discretized and solved by the iterative stabilized fractional step algorithm based on Crank-Nicolson implicit difference scheme. The moving free surface is captured and determined in terms of the stream function. The isothermal extrusion swelling simulations for low density polyethylene and linear low density polyethylene melts are investigated. Numerical results demonstrate good agreement of numerical results obtained by the proposed algorithm with those given in the literature and experiment results.