DOI: 10.1515/jaa-2026-0049 ISSN: 1425-6908

Singular limit for doubly nonlinear parabolic equations with absorption

Nguyen Duc Phuong

Abstract

We investigate the singular limit as

q → ∞ {q\to\infty}
for nonnegative weak solutions of a doubly nonlinear parabolic equation with absorption

geändert

∂ t ⁡ u q = div ⁡ ( | D ⁢ ( u q m ) | p - 2 ⁢ D ⁢ ( u q m ) ) - u q q   in  ⁢ ℝ N × ( 0 , ∞ ) . see text
\partial_{t}u_{q}=\operatorname{div}\bigl{(}|D(u_{q}^{m})|^{p-2}D(u_{q}^{m})% \bigr{)}-u_{q}^{q}\quad\text{in }\mathbb{R}^{N}\times(0,\infty).

Assuming

u 0 ≥ 0 {u_{0}\geq 0}
,
u 0 ∈ L 1 ⁢ ( ℝ N ) ∩ L ∞ ⁢ ( ℝ N ) ∩ C ⁢ ( ℝ N ) {u_{0}\in L^{1}(\mathbb{R}^{N})\cap L^{\infty}(\mathbb{R}^{N})\cap C(\mathbb{R% }^{N})}
,
m > 1 {m>1}
,
p > 1 {p>1}
, and
m ⁢ ( p - 1 ) > 1 {m(p-1)>1}
, we prove that
u q {u_{q}}
converges in
C ⁢ ( [ τ , T ] ; L 1 ⁢ ( ℝ N ) ) {C([\tau,T];L^{1}(\mathbb{R}^{N}))}
, for every
0 < τ < T {0<\tau<T}
, to the homogeneous flow with clipped initial datum
min ⁡ { u 0 , 1 } {\min\{u_{0},1\}}
. We derive explicit estimates for the residual absorption term on positive time intervals and establish a global
L 1 {L^{1}}
-comparison framework for the positive-time dynamics. We also characterize the associated initial layer and show that its size is exactly given by the super-threshold part
( u 0 - 1 ) + {(u_{0}-1)_{+}}
of the initial datum. The global residual absorption is
O ⁢ ( 1 q ) {O(\frac{1}{q})}
away from
t = 0 {t=0}
. A quantitative bound for the solution error also contains the
L 1 {L^{1}}
continuity moduli of the homogeneous flow at the initial data; an unconditional
O ⁢ ( 1 q ) {O(\frac{1}{q})}
rate for the solution error is not asserted.

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