• 제목/요약/키워드: parabolic equation

검색결과 251건 처리시간 0.024초

ANALYSIS OF THE VLASOV-POISSON EQUATION BY USING A VISCOSITY TERM

  • Choi, Boo-Yong;Kang, Sun-Bu;Lee, Moon-Shik
    • 충청수학회지
    • /
    • 제26권3호
    • /
    • pp.501-516
    • /
    • 2013
  • The well-known Vlasov-Poisson equation describes plasma physics as nonlinear first-order partial differential equations. Because of the nonlinear condition from the self consistency of the Vlasov-Poisson equation, many problems occur: the existence, the numerical solution, the convergence of the numerical solution, and so on. To solve the problems, a viscosity term (a second-order partial differential equation) is added. In a viscosity term, the Vlasov-Poisson equation changes into a parabolic equation like the Fokker-Planck equation. Therefore, the Schauder fixed point theorem and the classical results on parabolic equations can be used for analyzing the Vlasov-Poisson equation. The sequence and the convergence results are obtained from linearizing the Vlasove-Poisson equation by using a fixed point theorem and Gronwall's inequality. In numerical experiments, an implicit first-order scheme is used. The numerical results are tested using the changed viscosity terms.

BLOW-UP PHENOMENA FOR A QUASILINEAR PARABOLIC EQUATION WITH TIME-DEPENDENT COEFFICIENTS UNDER NONLINEAR BOUNDARY FLUX

  • Kwon, Tae In;Fang, Zhong Bo
    • 충청수학회지
    • /
    • 제31권3호
    • /
    • pp.287-308
    • /
    • 2018
  • This paper deals with blow-up phenomena for an initial boundary value problem of a quasilinear parabolic equation with time-dependent coefficient in a bounded star-shaped region under nonlinear boundary flux. Using the auxiliary function method and differential inequality technique, we establish some conditions on time-dependent coefficient and nonlinear functions for which the solution u(x, t) exists globally or blows up at some finite time $t^*$. Moreover, some upper and lower bounds for $t^*$ are derived in higher dimensional spaces. Some examples are presented to illustrate applications of our results.

UPPER SEMICONTINUITY OF PULLBACK ATTRACTORS FOR NON-AUTONOMOUS GENERALIZED 2D PARABOLIC EQUATIONS

  • PARK, JONG YEOUL;PARK, SUN-HYE
    • 대한수학회지
    • /
    • 제52권6호
    • /
    • pp.1149-1159
    • /
    • 2015
  • This paper is concerned with a generalized 2D parabolic equation with a nonautonomous perturbation $$-{\Delta}u_t+{\alpha}^2{\Delta}^2u_t+{\mu}{\Delta}^2u+{\bigtriangledown}{\cdot}{\vec{F}}(u)+B(u,u)={\epsilon}g(x,t)$$. Under some proper assumptions on the external force term g, the upper semicontinuity of pullback attractors is proved. More precisely, it is shown that the pullback attractor $\{A_{\epsilon}(t)\}_{t{\epsilon}{\mathbb{R}}}$ of the equation with ${\epsilon}>0$ converges to the global attractor A of the equation with ${\epsilon}=0$.

Global Attractivity and Oscillations in a Nonlinear Impulsive Parabolic Equation with Delay

  • Wang, Xiao;Li, Zhixiang
    • Kyungpook Mathematical Journal
    • /
    • 제48권4호
    • /
    • pp.593-611
    • /
    • 2008
  • Global attractivity and oscillatory behavior of the following nonlinear impulsive parabolic differential equation which is a general form of many population models $$\array{\{{{\frac {{\partial}u(t,x)}{{\partial}t}=\Delta}u(t,x)-{\delta}u(t,x)+f(u(t-\tau,x)),\;t{\neq}t_k,\\u(t^+_k,x)-u(t_k,x)=g_k(u(t_k,x)),\;k{\in}I_\infty,}\;\;\;\;\;\;\;\;(*)$$ are considered. Some new sufficient conditions for global attractivity and oscillation of the solutions of (*) with Neumann boundary condition are established. These results no only are true but also improve and complement existing results for (*) without diffusion or impulses. Moreover, when these results are applied to the Nicholson's blowflies model and the model of Hematopoiesis, some new results are obtained.

포물형 근사식에 의한 천해파 산정모델 (Wave Transformation Model in the Parabolic Approximation)

  • 서승남
    • 한국해안해양공학회지
    • /
    • 제2권3호
    • /
    • pp.134-142
    • /
    • 1990
  • 천해파랑의 변형을 추정하기 위한 광각 포물형 근사식이 제시되었다. 완경사 파랑식으로부터 분리행별법을 사용하여 유도된 포물형 근사식은 기존에 비해 일반화된 형태를 취하고 있다. 유한차분법에 의한 수치모델을 제시한 후 모델의 검증을 위해 원형천퇴 및 타원형천퇴의 수리모형 실험결과와 비교하였다. 수치결과는 거의 모든 점에서 실측치에 잘 부합되었고, 특히 회절현상이 뚜렷이 나타나는 천퇴 뒤편의 파랑특성을 잘 재현해 주었다.

  • PDF

NONHOMOGENEOUS DIRICHLET PROBLEM FOR ANISOTROPIC DEGENERATE PARABOLIC-HYPERBOLIC EQUATIONS WITH SPATIALLY DEPENDENT SECOND ORDER OPERATOR

  • Wang, Qin
    • 대한수학회보
    • /
    • 제53권6호
    • /
    • pp.1597-1612
    • /
    • 2016
  • There are fruitful results on degenerate parabolic-hyperbolic equations recently following the idea of $Kru{\check{z}}kov^{\prime}s$ doubling variables device. This paper is devoted to the well-posedness of nonhomogeneous boundary problem for degenerate parabolic-hyperbolic equations with spatially dependent second order operator, which has not caused much attention. The novelty is that we use the boundary flux triple instead of boundary layer to treat this problem.

SYMMETRY AND MONOTONICITY OF SOLUTIONS TO FRACTIONAL ELLIPTIC AND PARABOLIC EQUATIONS

  • Zeng, Fanqi
    • 대한수학회지
    • /
    • 제58권4호
    • /
    • pp.1001-1017
    • /
    • 2021
  • In this paper, we first apply parabolic inequalities and a maximum principle to give a new proof for symmetry and monotonicity of solutions to fractional elliptic equations with gradient term by the method of moving planes. Under the condition of suitable initial value, by maximum principles for the fractional parabolic equations, we obtain symmetry and monotonicity of positive solutions for each finite time to nonlinear fractional parabolic equations in a bounded domain and the whole space. More generally, if bounded domain is a ball, then we show that the solution is radially symmetric and monotone decreasing about the origin for each finite time. We firmly believe that parabolic inequalities and a maximum principle introduced here can be conveniently applied to study a variety of nonlocal elliptic and parabolic problems with more general operators and more general nonlinearities.

광안해역에서의 파랑변형예측 (Prediction of Wave Transformation in the Kwangan Beach)

  • 박정철;김재중;김인철
    • 한국해양공학회지
    • /
    • 제15권2호
    • /
    • pp.6-10
    • /
    • 2001
  • Water waves propagate over irregular bottom bathymetry are transformed by refraction, diffraction, shoaling, reflection etc. Principal factor of wave transform is bottom bathymetry, but in case of current field, current is another important factor which effect wave transformation. The governing equation of this study is develope as wave-current equation type to investigate the effect of wave-current interaction. It starts from Berkhoff's(1972) mild slope equation and is transformed to time-dependent hyperbolic type equation by using variational principal. Finally the governing equation is shown as a parabolic type equation by splitting method. This wave-current model was applied to the kwangan beach which is located at Pusan. The numerical simulation results of this model show the characteristics of wave transformation and flow pattern around the Kwangan beach fairly well.

  • PDF

인수분해 된 분모를 갖는 두 변수 유리함수 근사에 기반한 3차원 음향 포물선 방정식 제곱근 연산자의 분할기법 제안 (Suggestion for a splitting technique of the square-root operator of three dimensional acoustic parabolic equation based on two variable rational approximant with a factored denominator)

  • 이근화
    • 한국음향학회지
    • /
    • 제36권1호
    • /
    • pp.1-11
    • /
    • 2017
  • 본 연구에서는 두 변수 유리함수 근사법에 기반한 3차원 음향 포물선 방정식의 제곱근 연산자의 새로운 근사식을 제안한다. 이 근사식은 기존의 제곱근 연산자에 대한 근사 연구와 비교해서 두 가지의 장점을 가진다. 첫 번째는 광대역 각도 능력이다. 제안된 식은 방위각 $45^{\circ}$에서 3차원 음향 포물선 방정식의 거리 축으로부터 $62^{\circ}$까지 넓은 각도에 대해 정확도를 가지는데, 이 값은 기존에 연구된 3차원 음향 포물선 방정식 알고리즘의 각도 한계의 약 세 배이다. 두 번째로는 본 근사식의 분모는 수심과 횡 거리에 대한 연산자의 곱으로 표현된다는 점이다. 이러한 분할 형태는 3차원 포물선 방정식을 손쉽게 삼중대각행렬 방정식으로 변환할 수 있다는 점에서 수치해석에서 선호된다. 제안된 식의 성능을 검증하기 위해 위상 오차분석을 통해 타 근사법과의 비교 연구가 수행되었고, 제안된 방법은 가장 우수한 성능을 보였다.