<p>Several applications for systems of conservation laws of the form <InlineEquation ID="IEq1"> <EquationSource Format="MATHML"><math> <msub> <mi>U</mi> <mi>t</mi> </msub> <mo>+</mo> <msub> <mrow> <mo stretchy="false">(</mo> <mi mathvariant="normal">Φ</mi> <mo stretchy="false">(</mo> <mi>U</mi> <mo stretchy="false">)</mo> <mi>U</mi> <mo stretchy="false">)</mo> </mrow> <mi>x</mi> </msub> <mo>=</mo> <mn>0</mn> </math></EquationSource> <EquationSource Format="TEX">$U_{t} + (\Phi (U) U)_{x} =0$</EquationSource> </InlineEquation>, <InlineEquation ID="IEq2"> <EquationSource Format="MATHML"><math> <mi>U</mi> <mo>:</mo> <msub> <mi>R</mi> <mi>t</mi> </msub> <mo>×</mo> <msub> <mi>R</mi> <mi>x</mi> </msub> <mo stretchy="false">→</mo> <msup> <mi>R</mi> <mi>n</mi> </msup> </math></EquationSource> <EquationSource Format="TEX">$U: R_{t}\times R_{x}\rightarrow R^{n}$</EquationSource> </InlineEquation>, <InlineEquation ID="IEq3"> <EquationSource Format="MATHML"><math> <mi>n</mi> <mo>≥</mo> <mn>2</mn> </math></EquationSource> <EquationSource Format="TEX">$n\geq 2$</EquationSource> </InlineEquation>, with <InlineEquation ID="IEq4"> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">Φ</mi> <mo stretchy="false">(</mo> <mi>U</mi> <mo stretchy="false">)</mo> <mo>=</mo> <mi>ϕ</mi> <mo stretchy="false">(</mo> <mi>r</mi> <mo>,</mo> <mi mathvariant="normal">Θ</mi> <mo stretchy="false">)</mo> <mo>:</mo> <msup> <mi>R</mi> <mi>n</mi> </msup> <mo stretchy="false">→</mo> <mi>R</mi> </math></EquationSource> <EquationSource Format="TEX">$\Phi (U) = \phi (r, \Theta ): R^{n}\rightarrow R$</EquationSource> </InlineEquation>, <InlineEquation ID="IEq5"> <EquationSource Format="MATHML"><math> <mi>r</mi> <mo>=</mo> <mo stretchy="false">|</mo> <mi>U</mi> <mo stretchy="false">|</mo> </math></EquationSource> <EquationSource Format="TEX">$r = |U|$</EquationSource> </InlineEquation>, and <InlineEquation ID="IEq6"> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">Θ</mi> <mo>=</mo> <mi>U</mi> <mo stretchy="false">/</mo> <mo stretchy="false">|</mo> <mi>U</mi> <mo stretchy="false">|</mo> <mo>∈</mo> <msup> <mi>S</mi> <mrow> <mi>n</mi> <mo>−</mo> <mn>1</mn> </mrow> </msup> </math></EquationSource> <EquationSource Format="TEX">$\Theta = U/|U|\in S^{n-1}$</EquationSource> </InlineEquation>, are obtained by imposing structural conditions to provide a classification framework for solutions dependent on the form of <InlineEquation ID="IEq7"> <EquationSource Format="MATHML"><math> <mi>ϕ</mi> <mo stretchy="false">(</mo> <mi>U</mi> <mo stretchy="false">)</mo> </math></EquationSource> <EquationSource Format="TEX">$\phi (U)$</EquationSource> </InlineEquation>. By prescribing the evolution of a particular eigenvalue, we can categorize classes of such functions, <InlineEquation ID="IEq8"> <EquationSource Format="MATHML"><math> <mi>ϕ</mi> </math></EquationSource> <EquationSource Format="TEX">$\phi $</EquationSource> </InlineEquation>, for which this evolution is met, into depending on either a scalar field <InlineEquation ID="IEq9"> <EquationSource Format="MATHML"><math> <mi>z</mi> <mo>=</mo> <mi>r</mi> <mi>K</mi> <mo stretchy="false">(</mo> <mi mathvariant="normal">Θ</mi> <mo stretchy="false">)</mo> </math></EquationSource> <EquationSource Format="TEX">$z=rK(\Theta )$</EquationSource> </InlineEquation>, where <InlineEquation ID="IEq10"> <EquationSource Format="MATHML"><math> <mi>K</mi> <mo>:</mo> <msup> <mi>S</mi> <mrow> <mi>n</mi> <mo>−</mo> <mn>1</mn> </mrow> </msup> <mo stretchy="false">→</mo> <mi>R</mi> </math></EquationSource> <EquationSource Format="TEX">$K: S^{n-1}\rightarrow R$</EquationSource> </InlineEquation>, or on the vector field <InlineEquation ID="IEq11"> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">Θ</mi> </math></EquationSource> <EquationSource Format="TEX">$\Theta $</EquationSource> </InlineEquation>, and find for which the amplitude of solutions may blow up in finite time. As a consequence, solutions to the corresponding Riemann problems can be divided into those with are classical and those which involve delta-shocks and/or vacuum states.</p>

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Some Remarks on Structured Keyfitz-Kranzer Systems

  • Ralph Saxton,
  • Katarzyna Saxton

摘要

Several applications for systems of conservation laws of the form U t + ( Φ ( U ) U ) x = 0 $U_{t} + (\Phi (U) U)_{x} =0$ , U : R t × R x R n $U: R_{t}\times R_{x}\rightarrow R^{n}$ , n 2 $n\geq 2$ , with Φ ( U ) = ϕ ( r , Θ ) : R n R $\Phi (U) = \phi (r, \Theta ): R^{n}\rightarrow R$ , r = | U | $r = |U|$ , and Θ = U / | U | S n 1 $\Theta = U/|U|\in S^{n-1}$ , are obtained by imposing structural conditions to provide a classification framework for solutions dependent on the form of ϕ ( U ) $\phi (U)$ . By prescribing the evolution of a particular eigenvalue, we can categorize classes of such functions, ϕ $\phi $ , for which this evolution is met, into depending on either a scalar field z = r K ( Θ ) $z=rK(\Theta )$ , where K : S n 1 R $K: S^{n-1}\rightarrow R$ , or on the vector field Θ $\Theta $ , and find for which the amplitude of solutions may blow up in finite time. As a consequence, solutions to the corresponding Riemann problems can be divided into those with are classical and those which involve delta-shocks and/or vacuum states.