<p>This paper is concerned with the Keller-Segel system with flux limitation and nonlinear signal production <Equation ID="Equ84"> <MediaObject> <ImageObject Color="BlackWhite" FileRef="30_2025_1088_Article_Equ84.gif" Format="GIF" Height="54" Rendition="HTML" Resolution="72" Type="Linedraw" Width="366" /> </MediaObject> <EquationSource Format="TEX">\(\begin{aligned} \begin{aligned} \left\{ {\begin{array}{*{20}{l}} {{u_t} = \Delta u - \nabla \cdot \left( {uf(|\nabla v|^2)\nabla v} \right) ,}&amp; \\ {0 = \Delta v -\mu (t)+u^{\kappa },\quad \quad \mu (t):=\frac{1}{|\Omega |}\int _{\Omega } u^{\kappa }(x,t)dx}&amp; \end{array}} \right. \end{aligned} \end{aligned}\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mrow> <mtable> <mtr> <mtd columnalign="right"> <mrow> <mtable> <mtr> <mtd columnalign="right"> <mfenced open="{"> <mrow> <mtable> <mtr> <mtd columnalign="left"> <mrow> <msub> <mi>u</mi> <mi>t</mi> </msub> <mo>=</mo> <mi mathvariant="normal">Δ</mi> <mi>u</mi> <mo>-</mo> <mi mathvariant="normal">∇</mi> <mo>·</mo> <mfenced close=")" open="("> <mrow> <mi>u</mi> <mi>f</mi> <mo stretchy="false">(</mo> <mo stretchy="false">|</mo> <mi mathvariant="normal">∇</mi> <mi>v</mi> <msup> <mo stretchy="false">|</mo> <mn>2</mn> </msup> <mo stretchy="false">)</mo> <mi mathvariant="normal">∇</mi> <mi>v</mi> </mrow> </mfenced> <mo>,</mo> </mrow> </mtd> <mtd /> </mtr> <mtr> <mtd columnalign="left"> <mrow> <mrow /> <mrow> <mn>0</mn> <mo>=</mo> <mi mathvariant="normal">Δ</mi> <mi>v</mi> <mo>-</mo> <mi>μ</mi> <mrow> <mo stretchy="false">(</mo> <mi>t</mi> <mo stretchy="false">)</mo> </mrow> <mo>+</mo> <msup> <mi>u</mi> <mi>κ</mi> </msup> <mo>,</mo> <mspace width="1em" /> <mspace width="1em" /> <mi>μ</mi> <mrow> <mo stretchy="false">(</mo> <mi>t</mi> <mo stretchy="false">)</mo> </mrow> <mo>:</mo> <mo>=</mo> <mfrac> <mn>1</mn> <mrow> <mo stretchy="false">|</mo> <mi mathvariant="normal">Ω</mi> <mo stretchy="false">|</mo> </mrow> </mfrac> <msub> <mo>∫</mo> <mi mathvariant="normal">Ω</mi> </msub> <msup> <mi>u</mi> <mi>κ</mi> </msup> <mrow> <mo stretchy="false">(</mo> <mi>x</mi> <mo>,</mo> <mi>t</mi> <mo stretchy="false">)</mo> </mrow> <mi>d</mi> <mi>x</mi> </mrow> </mrow> </mtd> </mtr> </mtable> </mrow> </mfenced> </mtd> </mtr> </mtable> </mrow> </mtd> </mtr> </mtable> </mrow> </math></EquationSource> </Equation>in a smooth bounded domain <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="30_2025_1088_Article_IEq1.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="55" /> </InlineMediaObject> <EquationSource Format="TEX">\(\Omega \subset {\mathbb {R}^n}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="normal">Ω</mi> <mo>⊂</mo> <msup> <mrow> <mi mathvariant="double-struck">R</mi> </mrow> <mi>n</mi> </msup> </mrow> </math></EquationSource> </InlineEquation> <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="30_2025_1088_Article_IEq2.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="55" /> </InlineMediaObject> <EquationSource Format="TEX">\((n\ge 2)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">(</mo> <mi>n</mi> <mo>≥</mo> <mn>2</mn> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> with no-flux boundary conditions, where <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="30_2025_1088_Article_IEq3.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="66" /> </InlineMediaObject> <EquationSource Format="TEX">\(\kappa \in (0,1]\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>κ</mi> <mo>∈</mo> <mo stretchy="false">(</mo> <mn>0</mn> <mo>,</mo> <mn>1</mn> <mo stretchy="false">]</mo> </mrow> </math></EquationSource> </InlineEquation> and the function <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="30_2025_1088_Article_IEq4.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="109" /> </InlineMediaObject> <EquationSource Format="TEX">\(f\in C^2([0,\infty ))\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>f</mi> <mo>∈</mo> <msup> <mi>C</mi> <mn>2</mn> </msup> <mrow> <mo stretchy="false">(</mo> <mrow> <mo stretchy="false">[</mo> <mn>0</mn> <mo>,</mo> <mi>∞</mi> <mo stretchy="false">)</mo> </mrow> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> fulfills <Equation ID="Equ85"> <MediaObject> <ImageObject Color="BlackWhite" FileRef="30_2025_1088_Article_Equ85.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="231" /> </MediaObject> <EquationSource Format="TEX">\(\begin{aligned} f(\xi )=(1+\xi )^{-\alpha },\quad \text {for all }\xi \ge 0 \end{aligned}\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mrow> <mtable> <mtr> <mtd columnalign="right"> <mrow> <mi>f</mi> <mrow> <mo stretchy="false">(</mo> <mi>ξ</mi> <mo stretchy="false">)</mo> </mrow> <mo>=</mo> <msup> <mrow> <mo stretchy="false">(</mo> <mn>1</mn> <mo>+</mo> <mi>ξ</mi> <mo stretchy="false">)</mo> </mrow> <mrow> <mo>-</mo> <mi>α</mi> </mrow> </msup> <mo>,</mo> <mspace width="1em" /> <mtext>for all</mtext> <mspace width="0.333333em" /> <mi>ξ</mi> <mo>≥</mo> <mn>0</mn> </mrow> </mtd> </mtr> </mtable> </mrow> </math></EquationSource> </Equation>with <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="30_2025_1088_Article_IEq5.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="44" /> </InlineMediaObject> <EquationSource Format="TEX">\(\alpha \in \mathbb {R}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>α</mi> <mo>∈</mo> <mi mathvariant="double-struck">R</mi> </mrow> </math></EquationSource> </InlineEquation>. If either <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="30_2025_1088_Article_IEq5.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="44" /> </InlineMediaObject> <EquationSource Format="TEX">\(\alpha \in \mathbb {R}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>α</mi> <mo>∈</mo> <mi mathvariant="double-struck">R</mi> </mrow> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq7"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="30_2025_1088_Article_IEq7.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="74" /> </InlineMediaObject> <EquationSource Format="TEX">\(0&lt;\kappa \le \frac{1}{n}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>0</mn> <mo>&lt;</mo> <mi>κ</mi> <mo>≤</mo> <mfrac> <mn>1</mn> <mi>n</mi> </mfrac> </mrow> </math></EquationSource> </InlineEquation> or <InlineEquation ID="IEq8"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="30_2025_1088_Article_IEq8.gif" Format="GIF" Height="25" Rendition="HTML" Resolution="72" Type="Linedraw" Width="80" /> </InlineMediaObject> <EquationSource Format="TEX">\(\alpha &gt;\frac{n\kappa -2}{2(n\kappa -1)}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>α</mi> <mo>&gt;</mo> <mfrac> <mrow> <mi>n</mi> <mi>κ</mi> <mo>-</mo> <mn>2</mn> </mrow> <mrow> <mn>2</mn> <mo stretchy="false">(</mo> <mi>n</mi> <mi>κ</mi> <mo>-</mo> <mn>1</mn> <mo stretchy="false">)</mo> </mrow> </mfrac> </mrow> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq9"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="30_2025_1088_Article_IEq9.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="73" /> </InlineMediaObject> <EquationSource Format="TEX">\(\frac{1}{n}&lt;\kappa \le 1\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mfrac> <mn>1</mn> <mi>n</mi> </mfrac> <mo>&lt;</mo> <mi>κ</mi> <mo>≤</mo> <mn>1</mn> </mrow> </math></EquationSource> </InlineEquation>, then for suitably regular initial data, the solution of the corresponding initial-boundary value problem globally exists and is globally bounded. However, if <InlineEquation ID="IEq10"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="30_2025_1088_Article_IEq10.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="73" /> </InlineMediaObject> <EquationSource Format="TEX">\(\frac{2}{n}&lt;\kappa \le 1\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mfrac> <mn>2</mn> <mi>n</mi> </mfrac> <mo>&lt;</mo> <mi>κ</mi> <mo>≤</mo> <mn>1</mn> </mrow> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq11"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="30_2025_1088_Article_IEq11.gif" Format="GIF" Height="25" Rendition="HTML" Resolution="72" Type="Linedraw" Width="111" /> </InlineMediaObject> <EquationSource Format="TEX">\(0\le \alpha &lt;\frac{n\kappa -2}{2(n\kappa -1)}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>0</mn> <mo>≤</mo> <mi>α</mi> <mo>&lt;</mo> <mfrac> <mrow> <mi>n</mi> <mi>κ</mi> <mo>-</mo> <mn>2</mn> </mrow> <mrow> <mn>2</mn> <mo stretchy="false">(</mo> <mi>n</mi> <mi>κ</mi> <mo>-</mo> <mn>1</mn> <mo stretchy="false">)</mo> </mrow> </mfrac> </mrow> </math></EquationSource> </InlineEquation>, this system possesses radially symmetric solutions blowing up in finite time, confirming that the number <InlineEquation ID="IEq12"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="30_2025_1088_Article_IEq12.gif" Format="GIF" Height="25" Rendition="HTML" Resolution="72" Type="Linedraw" Width="80" /> </InlineMediaObject> <EquationSource Format="TEX">\(\alpha =\frac{n\kappa -2}{2(n\kappa -1)}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>α</mi> <mo>=</mo> <mfrac> <mrow> <mi>n</mi> <mi>κ</mi> <mo>-</mo> <mn>2</mn> </mrow> <mrow> <mn>2</mn> <mo stretchy="false">(</mo> <mi>n</mi> <mi>κ</mi> <mo>-</mo> <mn>1</mn> <mo stretchy="false">)</mo> </mrow> </mfrac> </mrow> </math></EquationSource> </InlineEquation> is critical in differentiating global existence from possible blow-up in the case <InlineEquation ID="IEq13"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="30_2025_1088_Article_IEq13.gif" Format="GIF" Height="15" Rendition="HTML" Resolution="72" Type="Linedraw" Width="43" /> </InlineMediaObject> <EquationSource Format="TEX">\(\alpha \ge 0\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>α</mi> <mo>≥</mo> <mn>0</mn> </mrow> </math></EquationSource> </InlineEquation>.</p>

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Finite-time blow-up in a Keller-Segel system with flux limitation and nonlinear signal production

  • Wenji Zhang

摘要

This paper is concerned with the Keller-Segel system with flux limitation and nonlinear signal production \(\begin{aligned} \begin{aligned} \left\{ {\begin{array}{*{20}{l}} {{u_t} = \Delta u - \nabla \cdot \left( {uf(|\nabla v|^2)\nabla v} \right) ,}& \\ {0 = \Delta v -\mu (t)+u^{\kappa },\quad \quad \mu (t):=\frac{1}{|\Omega |}\int _{\Omega } u^{\kappa }(x,t)dx}& \end{array}} \right. \end{aligned} \end{aligned}\) u t = Δ u - · u f ( | v | 2 ) v , 0 = Δ v - μ ( t ) + u κ , μ ( t ) : = 1 | Ω | Ω u κ ( x , t ) d x in a smooth bounded domain \(\Omega \subset {\mathbb {R}^n}\) Ω R n \((n\ge 2)\) ( n 2 ) with no-flux boundary conditions, where \(\kappa \in (0,1]\) κ ( 0 , 1 ] and the function \(f\in C^2([0,\infty ))\) f C 2 ( [ 0 , ) ) fulfills \(\begin{aligned} f(\xi )=(1+\xi )^{-\alpha },\quad \text {for all }\xi \ge 0 \end{aligned}\) f ( ξ ) = ( 1 + ξ ) - α , for all ξ 0 with \(\alpha \in \mathbb {R}\) α R . If either \(\alpha \in \mathbb {R}\) α R , \(0<\kappa \le \frac{1}{n}\) 0 < κ 1 n or \(\alpha >\frac{n\kappa -2}{2(n\kappa -1)}\) α > n κ - 2 2 ( n κ - 1 ) , \(\frac{1}{n}<\kappa \le 1\) 1 n < κ 1 , then for suitably regular initial data, the solution of the corresponding initial-boundary value problem globally exists and is globally bounded. However, if \(\frac{2}{n}<\kappa \le 1\) 2 n < κ 1 and \(0\le \alpha <\frac{n\kappa -2}{2(n\kappa -1)}\) 0 α < n κ - 2 2 ( n κ - 1 ) , this system possesses radially symmetric solutions blowing up in finite time, confirming that the number \(\alpha =\frac{n\kappa -2}{2(n\kappa -1)}\) α = n κ - 2 2 ( n κ - 1 ) is critical in differentiating global existence from possible blow-up in the case \(\alpha \ge 0\) α 0 .