# American Institute of Mathematical Sciences

May  2016, 21(3): 849-861. doi: 10.3934/dcdsb.2016.21.849

## Uniqueness of nonzero positive solutions of Laplacian elliptic equations arising in combustion theory

 1 Department of Mathematics, Ryerson University, Toronto, Ontario, M5B 2K3, Canada 2 School of Mathematical Sciences and Centre for Computational Systems Biology, Fudan University, Shanghai 200433, China

Received  September 2014 Revised  November 2015 Published  January 2016

Uniqueness of nonzero positive solutions of a Laplacian elliptic equation arising in combustion theory is of great interest in combustion theory since it can be applied to determine where the extinction phenomenon occurs. We study the uniqueness whenever the orders of the reaction rates are in $(-\infty,1]$. Previous results on uniqueness treated the case when the orders belong to $[0,1)$. When the orders are negative or 1, it is physically meaningful and the bimolecular reaction rate corresponds to the order 1, but there is little study on uniqueness. Our results on the uniqueness are completely new when the orders are negative or 1, and also improve some known results when the orders belong to $(0,1)$. Our results provide exact intervals of the Frank-Kamenetskii parameters on which the extinction phenomenon never occurs. The novelty of our methodology is to combine and utilize the results from Laplacian elliptic inequalities and equations to derive new results on uniqueness of nonzero positive solutions for general Laplacian elliptic equations.
Citation: Kunquan Lan, Wei Lin. Uniqueness of nonzero positive solutions of Laplacian elliptic equations arising in combustion theory. Discrete & Continuous Dynamical Systems - B, 2016, 21 (3) : 849-861. doi: 10.3934/dcdsb.2016.21.849
##### References:
 [1] I. Ali, A. Castro and R. Shivaji, Uniqueness and stability of nonnegative solutions for semipositone problems in a ball,, Proc. Amer. Math. Soc., 117 (1993), 775. doi: 10.1090/S0002-9939-1993-1116249-5. Google Scholar [2] H. Amann, On the existence of positive solutions of nonlinear elliptic boundary problems,, Indiana Univ. Math. J., 71 (1972), 125. doi: 10.1512/iumj.1972.21.21012. Google Scholar [3] T. Boddington, P. Gray and C. Robinson, Thermal explosion and the disappearance of criticality at small activation energies: Exact results for the slab,, Proc. Roy. Soc. London, 368 (1979), 441. Google Scholar [4] H. Brezis and L. Oswald, Remarks on sublinear elliptic equations,, Nonlinear Anal. 10 (1986), 10 (1986), 55. doi: 10.1016/0362-546X(86)90011-8. Google Scholar [5] K. J. Brown, M. M. A. Ibrahim and R. Shivaji, S-shaped bifurcation curves,, Nonlinear Anal., 5 (1981), 475. doi: 10.1016/0362-546X(81)90096-1. Google Scholar [6] N. P. Cac, On the uniqueness of positive solutions of a nonlinear elliptic boundary value problems,, J. London Math. Soc., 25 (1982), 347. doi: 10.1112/jlms/s2-25.2.347. Google Scholar [7] Y. H. Du, Exact multiplicity and S-shaped bifurcation curve for some semilinear elliptic problems from combustion theory,, SIAM J. Math. Anal., 32 (2000), 707. doi: 10.1137/S0036141098343586. Google Scholar [8] Y. H. Du and Y. Lou, Proof of a conjecture for the perturbed Gelfand equation from combustion theory,, J. Differential Equations, 173 (2001), 213. doi: 10.1006/jdeq.2000.3932. Google Scholar [9] B. Gidas, W. M. Ni and L. Nirenberg, Symmetry and related properties via the maximum principle,, Comm. Math. Phys., 68 (1977), 209. doi: 10.1007/BF01221125. Google Scholar [10] P. Hess, On the uniqueness of positive solutions of nonlinear elliptic boundary value problems,, Math. Z., 154 (1977), 17. doi: 10.1007/BF01215108. Google Scholar [11] W. P. Ho, R. B. Barat and J. W. Bozzelli, Thermal reaction of CH2C12 in H2/02 mixtures: Implications for chlorine inhibition of CO conversion to CO2,, Combust. Flame, 88 (1992), 265. Google Scholar [12] K. Q. Lan, Nonzero positive solutions of systems of elliptic boundary value problems,, Proc. Amer. Math. Soc., 139 (2011), 4343. doi: 10.1090/S0002-9939-2011-10840-2. Google Scholar [13] K. Q. Lan, A variational inequality theory for demicontinuous S-contractive maps with applications to semilinear elliptic inequalities,, J. Differential Equations, 246 (2009), 909. doi: 10.1016/j.jde.2008.10.007. Google Scholar [14] K. Q. Lan, Positive weak solutions of semilinear second order elliptic inequalities via variational inequalities,, J. Math. Anal. Appl., 380 (2011), 520. doi: 10.1016/j.jmaa.2011.03.030. Google Scholar [15] K. Q. Lan, A fixed point theory for weakly inward S-contractive maps,, Nonlinear Anal., 45 (2001), 189. doi: 10.1016/S0362-546X(99)00337-5. Google Scholar [16] K. Q. Lan and W. Lin, A variational inequality index for condensing maps in Hilbert spaces and applications to semilinear elliptic inequalities,, Nonlinear Anal., 74 (2011), 5415. doi: 10.1016/j.na.2011.05.025. Google Scholar [17] K. Q. Lan and J. R. L. Webb, Variational inequalities and fixed point theorems for PM-maps,, J. Math. Anal. Appl., 224 (1998), 102. doi: 10.1006/jmaa.1998.5988. Google Scholar [18] K. Q. Lan and J. R. L. Webb, Positive solutions of semilinear differential equations with singularities,, J. Differential Equations, 148 (1998), 407. doi: 10.1006/jdeq.1998.3475. Google Scholar [19] K. Q. Lan and Z. Zhang, Nonzero positive weak solutions of systems of p-Laplace equations,, J. Math. Anal. Appl., 394 (2012), 581. doi: 10.1016/j.jmaa.2012.04.061. Google Scholar [20] P. L. Lions, On the existence of positive solutions of semilinear elliptic equations,, SIAM Rev., 24 (1982), 441. doi: 10.1137/1024101. Google Scholar [21] G. P. Miller, The structure of a stoichiometric CCI4-CH4-air flat flame,, Combust. Flame, 101 (1995), 101. Google Scholar [22] W. M. Ni, Uniqueness of solutions of nonlinear Dirichelet problems,, J. Differential Equations, 50 (1983), 289. doi: 10.1016/0022-0396(83)90079-7. Google Scholar [23] W. M. Ni and R. D. Nussbaum, Uniqueness and nonuniqueness for positive radial solutions of $\Delta u+f(u,r)=0$,, Comm. Pure Appl. Math., 38 (1985), 67. doi: 10.1002/cpa.3160380105. Google Scholar [24] S. S. Okoya, Boundness for a system of reaction-diffusion equations. I,, Mathematika, 41 (1994), 293. doi: 10.1112/S0025579300007397. Google Scholar [25] J. A. Smoller and A. G. Wasserman, Existence, uniqueness, and non degeneracy of positive solutions of semilinear elliptic equations,, Comm. Math. Phys., 95 (1984), 129. doi: 10.1007/BF01468138. Google Scholar [26] K. Taira, Semilinear elliptic boundary-value problems in combustion theory,, Proc. Roy. Soc. Edinburgh, 132 (2002), 1453. Google Scholar [27] D. G. Vlachos, The interplay of transport, kinetics, and thermal interactions in the stability of premixed hydrogen/air flames,, Combust. Flame, 103 (1995), 59. doi: 10.1016/0010-2180(95)00072-E. Google Scholar [28] G. C. Wake, T. Boddington and P. Gray, Thermal explosion and the disappearance of criticality in systems with distribution temperatures, IV. Rigonus bounds and their practical relevance,, Proc. Roy. Soc. London, 425 (1989), 285. Google Scholar [29] S. H. Wang, On S-shaped bifurcation curves,, Nonlinear Anal., 22 (1994), 1475. doi: 10.1016/0362-546X(94)90183-X. Google Scholar [30] S. H. Wang, Rigorous analysis and estimates of S-shaped bifurcation curves in a combustion problem with general Arrhenius reaction-rate laws,, Proc. Roy. Soc. London, 454 (1998), 1031. doi: 10.1098/rspa.1998.0195. Google Scholar [31] F. A. Williams, Combustion theory, 2nd ed,, Redwood City, (1985), 585. Google Scholar

show all references

##### References:
 [1] I. Ali, A. Castro and R. Shivaji, Uniqueness and stability of nonnegative solutions for semipositone problems in a ball,, Proc. Amer. Math. Soc., 117 (1993), 775. doi: 10.1090/S0002-9939-1993-1116249-5. Google Scholar [2] H. Amann, On the existence of positive solutions of nonlinear elliptic boundary problems,, Indiana Univ. Math. J., 71 (1972), 125. doi: 10.1512/iumj.1972.21.21012. Google Scholar [3] T. Boddington, P. Gray and C. Robinson, Thermal explosion and the disappearance of criticality at small activation energies: Exact results for the slab,, Proc. Roy. Soc. London, 368 (1979), 441. Google Scholar [4] H. Brezis and L. Oswald, Remarks on sublinear elliptic equations,, Nonlinear Anal. 10 (1986), 10 (1986), 55. doi: 10.1016/0362-546X(86)90011-8. Google Scholar [5] K. J. Brown, M. M. A. Ibrahim and R. Shivaji, S-shaped bifurcation curves,, Nonlinear Anal., 5 (1981), 475. doi: 10.1016/0362-546X(81)90096-1. Google Scholar [6] N. P. Cac, On the uniqueness of positive solutions of a nonlinear elliptic boundary value problems,, J. London Math. Soc., 25 (1982), 347. doi: 10.1112/jlms/s2-25.2.347. Google Scholar [7] Y. H. Du, Exact multiplicity and S-shaped bifurcation curve for some semilinear elliptic problems from combustion theory,, SIAM J. Math. Anal., 32 (2000), 707. doi: 10.1137/S0036141098343586. Google Scholar [8] Y. H. Du and Y. Lou, Proof of a conjecture for the perturbed Gelfand equation from combustion theory,, J. Differential Equations, 173 (2001), 213. doi: 10.1006/jdeq.2000.3932. Google Scholar [9] B. Gidas, W. M. Ni and L. Nirenberg, Symmetry and related properties via the maximum principle,, Comm. Math. Phys., 68 (1977), 209. doi: 10.1007/BF01221125. Google Scholar [10] P. Hess, On the uniqueness of positive solutions of nonlinear elliptic boundary value problems,, Math. Z., 154 (1977), 17. doi: 10.1007/BF01215108. Google Scholar [11] W. P. Ho, R. B. Barat and J. W. Bozzelli, Thermal reaction of CH2C12 in H2/02 mixtures: Implications for chlorine inhibition of CO conversion to CO2,, Combust. Flame, 88 (1992), 265. Google Scholar [12] K. Q. Lan, Nonzero positive solutions of systems of elliptic boundary value problems,, Proc. Amer. Math. Soc., 139 (2011), 4343. doi: 10.1090/S0002-9939-2011-10840-2. Google Scholar [13] K. Q. Lan, A variational inequality theory for demicontinuous S-contractive maps with applications to semilinear elliptic inequalities,, J. Differential Equations, 246 (2009), 909. doi: 10.1016/j.jde.2008.10.007. Google Scholar [14] K. Q. Lan, Positive weak solutions of semilinear second order elliptic inequalities via variational inequalities,, J. Math. Anal. Appl., 380 (2011), 520. doi: 10.1016/j.jmaa.2011.03.030. Google Scholar [15] K. Q. Lan, A fixed point theory for weakly inward S-contractive maps,, Nonlinear Anal., 45 (2001), 189. doi: 10.1016/S0362-546X(99)00337-5. Google Scholar [16] K. Q. Lan and W. Lin, A variational inequality index for condensing maps in Hilbert spaces and applications to semilinear elliptic inequalities,, Nonlinear Anal., 74 (2011), 5415. doi: 10.1016/j.na.2011.05.025. Google Scholar [17] K. Q. Lan and J. R. L. Webb, Variational inequalities and fixed point theorems for PM-maps,, J. Math. Anal. Appl., 224 (1998), 102. doi: 10.1006/jmaa.1998.5988. Google Scholar [18] K. Q. Lan and J. R. L. Webb, Positive solutions of semilinear differential equations with singularities,, J. Differential Equations, 148 (1998), 407. doi: 10.1006/jdeq.1998.3475. Google Scholar [19] K. Q. Lan and Z. Zhang, Nonzero positive weak solutions of systems of p-Laplace equations,, J. Math. Anal. Appl., 394 (2012), 581. doi: 10.1016/j.jmaa.2012.04.061. Google Scholar [20] P. L. Lions, On the existence of positive solutions of semilinear elliptic equations,, SIAM Rev., 24 (1982), 441. doi: 10.1137/1024101. Google Scholar [21] G. P. Miller, The structure of a stoichiometric CCI4-CH4-air flat flame,, Combust. Flame, 101 (1995), 101. Google Scholar [22] W. M. Ni, Uniqueness of solutions of nonlinear Dirichelet problems,, J. Differential Equations, 50 (1983), 289. doi: 10.1016/0022-0396(83)90079-7. Google Scholar [23] W. M. Ni and R. D. Nussbaum, Uniqueness and nonuniqueness for positive radial solutions of $\Delta u+f(u,r)=0$,, Comm. Pure Appl. Math., 38 (1985), 67. doi: 10.1002/cpa.3160380105. Google Scholar [24] S. S. Okoya, Boundness for a system of reaction-diffusion equations. I,, Mathematika, 41 (1994), 293. doi: 10.1112/S0025579300007397. Google Scholar [25] J. A. Smoller and A. G. Wasserman, Existence, uniqueness, and non degeneracy of positive solutions of semilinear elliptic equations,, Comm. Math. Phys., 95 (1984), 129. doi: 10.1007/BF01468138. Google Scholar [26] K. Taira, Semilinear elliptic boundary-value problems in combustion theory,, Proc. Roy. Soc. Edinburgh, 132 (2002), 1453. Google Scholar [27] D. G. Vlachos, The interplay of transport, kinetics, and thermal interactions in the stability of premixed hydrogen/air flames,, Combust. Flame, 103 (1995), 59. doi: 10.1016/0010-2180(95)00072-E. Google Scholar [28] G. C. Wake, T. Boddington and P. Gray, Thermal explosion and the disappearance of criticality in systems with distribution temperatures, IV. Rigonus bounds and their practical relevance,, Proc. Roy. Soc. London, 425 (1989), 285. Google Scholar [29] S. H. Wang, On S-shaped bifurcation curves,, Nonlinear Anal., 22 (1994), 1475. doi: 10.1016/0362-546X(94)90183-X. Google Scholar [30] S. H. Wang, Rigorous analysis and estimates of S-shaped bifurcation curves in a combustion problem with general Arrhenius reaction-rate laws,, Proc. Roy. Soc. London, 454 (1998), 1031. doi: 10.1098/rspa.1998.0195. Google Scholar [31] F. A. Williams, Combustion theory, 2nd ed,, Redwood City, (1985), 585. Google Scholar
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