Coercive elliptic systems with gradient terms

2017 ◽  
Vol 6 (2) ◽  
pp. 165-182 ◽  
Author(s):  
Roberta Filippucci ◽  
Federico Vinti

AbstractIn this paper we give a classification of positive radial solutions of the following system:$\Delta u=v^{m},\quad\Delta v=h(|x|)g(u)f(|\nabla u|),$in the open ball ${B_{R}}$, with ${m>0}$, and f, g, h nonnegative nondecreasing continuous functions. In particular, we deal with both explosive and bounded solutions. Our results involve, as in [27], a generalization of the well-known Keller–Osserman condition, namely, ${\int_{1}^{\infty}(\int_{0}^{s}F(t)\,dt)^{-m/(2m+1)}\,ds<\infty}$, where ${F(t)=\int_{0}^{t}f(s)\,ds}$. Moreover, in the second part of the paper, the p-Laplacian version, given by ${\Delta_{p}u=v^{m}}$, ${\Delta_{p}v=f(|\nabla u|)}$, is treated. When ${p\geq 2}$, we prove a necessary condition for the existence of a solution with at least a blow up component at the boundary, precisely ${\int_{1}^{\infty}(\int_{0}^{s}F(t)\,dt)^{-m/(mp+p-1)}s^{(p-2)(p-1)/(mp+p-1)}% \,ds<\infty}$.

2020 ◽  
Vol 20 (2) ◽  
pp. 293-310
Author(s):  
Marta García-Huidobro ◽  
Raúl Manasevich ◽  
Satoshi Tanaka

AbstractIn this paper we deal with positive radially symmetric solutions for a boundary value problem containing a strongly nonlinear operator. The proof of existence of positive solutions that we give uses the blow-up method as a main ingredient for the search of a-priori bounds of solutions. The blow-up argument is one by contradiction and uses a sort of scaling, reminiscent to the one used in the theory of minimal surfaces, see [B. Gidas and J. Spruck, A priori bounds for positive solutions of nonlinear elliptic equations, Comm. Partial Differential Equations 6 1981, 883–901], and therefore the homogeneity of the operators, Laplacian or p-Laplacian, and second members powers or power like functions play a fundamental role in the method. Thus, when the differential operators are no longer homogeneous, and similarly for the second members, applying the blow-up method to obtain a-priori bounds of solutions seems an almost impossible task. In spite of this fact, in [M. García-Huidobro, I. Guerra and R. Manásevich, Existence of positive radial solutions for a weakly coupled system via blow up, Abstr. Appl. Anal. 3 1998, 1–2, 105–131], we were able to overcome this difficulty and obtain a-priori bounds for a certain (simpler) type of problems. We show in this paper that the asymptotically homogeneous functions provide, in the same sense, a nonlinear rescaling, that allows us to generalize the blow-up method to our present situation. After the a-priori bounds are obtained, the existence of a solution follows from Leray–Schauder topological degree theory.


2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Yongju Yang ◽  
Xinguang Zhang

We study the existence of entire positive solutions for the semilinear elliptic system with quadratic gradient terms,Δui+|∇ui|2=pi(|x|)fi(u1,u2,…,ud)fori=1,2,…,donRN,N≥3andd∈{1,2,3,…}. We establish the conditions onpithat ensure the existence of nonnegative radial solutions blowing up at infinity and also the conditions for bounded solutions on the entire space. The condition onfiis simple and different to the Keller-Osserman condition.


2013 ◽  
Vol 29 (2) ◽  
pp. 187-193
Author(s):  
MIODRAG IOVANOV ◽  

We obtain sufficient conditions for the non-existence of positive radially symmetric solutions for a class of Lane, Emden and Fowler elliptic systems. In our result, the nonlinear term it was suggested by the work of [D. O’Regan and H. Wang, Positive radial solutions for p-Laplacian systems, Aequationes Math., 75 (2008) 43–50].


Author(s):  
Xinguang Zhang ◽  
Lishan Liu ◽  
Yonghong Wu ◽  
Yujun Cui

In this paper, we establish the results of nonexistence and existence of blow-up radial solutions for a k-Hessian equation with a nonlinear operator. Under some suitable growth conditions for nonlinearity, the result of nonexistence of blow-up solutions is established, a sufficient and necessary condition on existence of blow-up solutions is given, and some further results are obtained. 


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