<p>In this paper, we consider a doubly degenerate taxis system of the form <Equation ID="Equ107"> <EquationSource Format="TEX">\(\begin{aligned} \left\{ \begin{array}{rllc} u_{t}&amp; =\nabla \cdot \big (uv\nabla u\big )-\nabla \cdot \big (u^2v\nabla v\big ),\ &amp; x\in \Omega ,&amp; t&gt;0,\\ v_{t}&amp; =\Delta v-f(u)v,\ &amp; x\in \Omega ,&amp; t&gt;0, \end{array}\right. \end{aligned}\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mrow> <mtable> <mtr> <mtd columnalign="right"> <mfenced open="{"> <mrow> <mtable> <mtr> <mtd columnalign="right"> <msub> <mi>u</mi> <mi>t</mi> </msub> </mtd> <mtd columnalign="left"> <mrow> <mo>=</mo> <mi mathvariant="normal">∇</mi> <mo>·</mo> <mrow> <mo maxsize="1.2em" minsize="1.2em" stretchy="true">(</mo> </mrow> <mi>u</mi> <mi>v</mi> <mi mathvariant="normal">∇</mi> <mi>u</mi> <mrow> <mo maxsize="1.2em" minsize="1.2em" stretchy="true">)</mo> </mrow> <mo>-</mo> <mi mathvariant="normal">∇</mi> <mo>·</mo> <mrow> <mo maxsize="1.2em" minsize="1.2em" stretchy="true">(</mo> </mrow> <msup> <mi>u</mi> <mn>2</mn> </msup> <mi>v</mi> <mi mathvariant="normal">∇</mi> <mi>v</mi> <mrow> <mo maxsize="1.2em" minsize="1.2em" stretchy="true">)</mo> </mrow> <mo>,</mo> <mspace width="4pt" /> </mrow> </mtd> <mtd columnalign="left"> <mrow> <mi>x</mi> <mo>∈</mo> <mi mathvariant="normal">Ω</mi> <mo>,</mo> </mrow> </mtd> <mtd> <mrow> <mi>t</mi> <mo>&gt;</mo> <mn>0</mn> <mo>,</mo> </mrow> </mtd> </mtr> <mtr> <mtd columnalign="right"> <mrow> <mrow /> <msub> <mi>v</mi> <mi>t</mi> </msub> </mrow> </mtd> <mtd columnalign="left"> <mrow> <mo>=</mo> <mi mathvariant="normal">Δ</mi> <mi>v</mi> <mo>-</mo> <mi>f</mi> <mo stretchy="false">(</mo> <mi>u</mi> <mo stretchy="false">)</mo> <mi>v</mi> <mo>,</mo> <mspace width="4pt" /> </mrow> </mtd> <mtd columnalign="left"> <mrow> <mi>x</mi> <mo>∈</mo> <mi mathvariant="normal">Ω</mi> <mo>,</mo> </mrow> </mtd> <mtd> <mrow> <mi>t</mi> <mo>&gt;</mo> <mn>0</mn> <mo>,</mo> </mrow> </mtd> </mtr> </mtable> </mrow> </mfenced> </mtd> </mtr> </mtable> </mrow> </math></EquationSource> </Equation>in a smoothly bounded domain <InlineEquation ID="IEq1"> <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"> <EquationSource Format="TEX">\(N\ge 2\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>N</mi> <mo>≥</mo> <mn>2</mn> </mrow> </math></EquationSource> </InlineEquation>. The function <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(f\in C^1([0,\infty ))\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>f</mi> <mo>∈</mo> <msup> <mi>C</mi> <mn>1</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> is assumed to satisfy the constraints <Equation ID="Equ108"> <EquationSource Format="TEX">\(\begin{aligned} f(s)\ge c_f s^\alpha \quad \text {for all }s\ge 1\quad \text {and}\quad f(s)\le C_f s^\alpha \quad \text {for all }s&gt;0 \end{aligned}\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mrow> <mtable> <mtr> <mtd columnalign="right"> <mrow> <mi>f</mi> <mrow> <mo stretchy="false">(</mo> <mi>s</mi> <mo stretchy="false">)</mo> </mrow> <mo>≥</mo> <msub> <mi>c</mi> <mi>f</mi> </msub> <msup> <mi>s</mi> <mi>α</mi> </msup> <mspace width="1em" /> <mtext>for all</mtext> <mspace width="0.333333em" /> <mi>s</mi> <mo>≥</mo> <mn>1</mn> <mspace width="1em" /> <mtext>and</mtext> <mspace width="1em" /> <mi>f</mi> <mrow> <mo stretchy="false">(</mo> <mi>s</mi> <mo stretchy="false">)</mo> </mrow> <mo>≤</mo> <msub> <mi>C</mi> <mi>f</mi> </msub> <msup> <mi>s</mi> <mi>α</mi> </msup> <mspace width="1em" /> <mtext>for all</mtext> <mspace width="0.333333em" /> <mi>s</mi> <mo>&gt;</mo> <mn>0</mn> </mrow> </mtd> </mtr> </mtable> </mrow> </math></EquationSource> </Equation>for <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(\alpha \in (0,\tfrac{2}{N})\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>α</mi> <mo>∈</mo> <mo stretchy="false">(</mo> <mn>0</mn> <mo>,</mo> <mstyle displaystyle="false" scriptlevel="0"> <mfrac> <mn>2</mn> <mi>N</mi> </mfrac> </mstyle> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> and constants <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(C_f,c_f&gt;0\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>C</mi> <mi>f</mi> </msub> <mo>,</mo> <msub> <mi>c</mi> <mi>f</mi> </msub> <mo>&gt;</mo> <mn>0</mn> </mrow> </math></EquationSource> </InlineEquation>. We establish the existence of a global continuous weak solution which remains bounded for all times, without any condition on the initial data beyond regularity assumptions. Moreover, we obtain convergence toward <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\((u_\infty ,0)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">(</mo> <msub> <mi>u</mi> <mi>∞</mi> </msub> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> in the large-time limit, where the limit function <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(u_\infty =w(\cdot ,1)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>u</mi> <mi>∞</mi> </msub> <mo>=</mo> <mi>w</mi> <mrow> <mo stretchy="false">(</mo> <mo>·</mo> <mo>,</mo> <mn>1</mn> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> is provided by the weak solution of the associated parabolic PDE <Equation ID="Equ109"> <EquationSource Format="TEX">\(\begin{aligned} w_{\tau }=\nabla \cdot \big (a(x,\tau )w\nabla w\big )-\nabla \cdot \big (b(x,\tau )w^2\big ),\quad x\in \Omega ,\ \tau \in (0,1), \end{aligned}\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mrow> <mtable> <mtr> <mtd columnalign="right"> <mrow> <msub> <mi>w</mi> <mi>τ</mi> </msub> <mo>=</mo> <mi mathvariant="normal">∇</mi> <mo>·</mo> <mrow> <mo maxsize="1.2em" minsize="1.2em" stretchy="true">(</mo> </mrow> <mi>a</mi> <mrow> <mo stretchy="false">(</mo> <mi>x</mi> <mo>,</mo> <mi>τ</mi> <mo stretchy="false">)</mo> </mrow> <mi>w</mi> <mi mathvariant="normal">∇</mi> <mi>w</mi> <mrow> <mo maxsize="1.2em" minsize="1.2em" stretchy="true">)</mo> </mrow> <mo>-</mo> <mi mathvariant="normal">∇</mi> <mo>·</mo> <mrow> <mo maxsize="1.2em" minsize="1.2em" stretchy="true">(</mo> </mrow> <mi>b</mi> <mrow> <mo stretchy="false">(</mo> <mi>x</mi> <mo>,</mo> <mi>τ</mi> <mo stretchy="false">)</mo> </mrow> <msup> <mi>w</mi> <mn>2</mn> </msup> <mrow> <mo maxsize="1.2em" minsize="1.2em" stretchy="true">)</mo> </mrow> <mo>,</mo> <mspace width="1em" /> <mi>x</mi> <mo>∈</mo> <mi mathvariant="normal">Ω</mi> <mo>,</mo> <mspace width="4pt" /> <mi>τ</mi> <mo>∈</mo> <mrow> <mo stretchy="false">(</mo> <mn>0</mn> <mo>,</mo> <mn>1</mn> <mo stretchy="false">)</mo> </mrow> <mo>,</mo> </mrow> </mtd> </mtr> </mtable> </mrow> </math></EquationSource> </Equation>where the coefficients <InlineEquation ID="IEq8"> <EquationSource Format="TEX">\(a(x,\tau )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>a</mi> <mo stretchy="false">(</mo> <mi>x</mi> <mo>,</mo> <mi>τ</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq9"> <EquationSource Format="TEX">\(b(x,\tau )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>b</mi> <mo stretchy="false">(</mo> <mi>x</mi> <mo>,</mo> <mi>τ</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> are defined intrinsically as appropriately rescaled quantities of <i>v</i> and <InlineEquation ID="IEq10"> <EquationSource Format="TEX">\(v\nabla v\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>v</mi> <mi mathvariant="normal">∇</mi> <mi>v</mi> </mrow> </math></EquationSource> </InlineEquation>, respectively.</p>

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Global solvability and large-time behavior in a doubly degenerate migration model involving saturated signal consumption

  • Tobias Black,
  • Shohei Kohatsu,
  • Duan Wu

摘要

In this paper, we consider a doubly degenerate taxis system of the form \(\begin{aligned} \left\{ \begin{array}{rllc} u_{t}& =\nabla \cdot \big (uv\nabla u\big )-\nabla \cdot \big (u^2v\nabla v\big ),\ & x\in \Omega ,& t>0,\\ v_{t}& =\Delta v-f(u)v,\ & x\in \Omega ,& t>0, \end{array}\right. \end{aligned}\) u t = · ( u v u ) - · ( u 2 v v ) , x Ω , t > 0 , v t = Δ v - f ( u ) v , x Ω , t > 0 , in a smoothly bounded domain \(\Omega \subset \mathbb {R}^N\) Ω R N , \(N\ge 2\) N 2 . The function \(f\in C^1([0,\infty ))\) f C 1 ( [ 0 , ) ) is assumed to satisfy the constraints \(\begin{aligned} f(s)\ge c_f s^\alpha \quad \text {for all }s\ge 1\quad \text {and}\quad f(s)\le C_f s^\alpha \quad \text {for all }s>0 \end{aligned}\) f ( s ) c f s α for all s 1 and f ( s ) C f s α for all s > 0 for \(\alpha \in (0,\tfrac{2}{N})\) α ( 0 , 2 N ) and constants \(C_f,c_f>0\) C f , c f > 0 . We establish the existence of a global continuous weak solution which remains bounded for all times, without any condition on the initial data beyond regularity assumptions. Moreover, we obtain convergence toward \((u_\infty ,0)\) ( u , 0 ) in the large-time limit, where the limit function \(u_\infty =w(\cdot ,1)\) u = w ( · , 1 ) is provided by the weak solution of the associated parabolic PDE \(\begin{aligned} w_{\tau }=\nabla \cdot \big (a(x,\tau )w\nabla w\big )-\nabla \cdot \big (b(x,\tau )w^2\big ),\quad x\in \Omega ,\ \tau \in (0,1), \end{aligned}\) w τ = · ( a ( x , τ ) w w ) - · ( b ( x , τ ) w 2 ) , x Ω , τ ( 0 , 1 ) , where the coefficients \(a(x,\tau )\) a ( x , τ ) and \(b(x,\tau )\) b ( x , τ ) are defined intrinsically as appropriately rescaled quantities of v and \(v\nabla v\) v v , respectively.