Estimate the large-time behavior of the unique viscosity solution












2














I am looking for some help to determine the large-time behavior of the unique solution for the equation in $mathbb R^+ times mathbb R$ $$u_t+vertnabla uvert^frac{2}{3}=0, u(0,x)=-cos x$$
More specifically, I am thinking about how to determine the behavior of u at $(2015,0)$ or $(n,0)$ for any large integer $n$, but I have no idea that where to start.



Many thanks to the help in advance.










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    I am looking for some help to determine the large-time behavior of the unique solution for the equation in $mathbb R^+ times mathbb R$ $$u_t+vertnabla uvert^frac{2}{3}=0, u(0,x)=-cos x$$
    More specifically, I am thinking about how to determine the behavior of u at $(2015,0)$ or $(n,0)$ for any large integer $n$, but I have no idea that where to start.



    Many thanks to the help in advance.










    share|cite|improve this question



























      2












      2








      2


      1





      I am looking for some help to determine the large-time behavior of the unique solution for the equation in $mathbb R^+ times mathbb R$ $$u_t+vertnabla uvert^frac{2}{3}=0, u(0,x)=-cos x$$
      More specifically, I am thinking about how to determine the behavior of u at $(2015,0)$ or $(n,0)$ for any large integer $n$, but I have no idea that where to start.



      Many thanks to the help in advance.










      share|cite|improve this question















      I am looking for some help to determine the large-time behavior of the unique solution for the equation in $mathbb R^+ times mathbb R$ $$u_t+vertnabla uvert^frac{2}{3}=0, u(0,x)=-cos x$$
      More specifically, I am thinking about how to determine the behavior of u at $(2015,0)$ or $(n,0)$ for any large integer $n$, but I have no idea that where to start.



      Many thanks to the help in advance.







      pde hamilton-jacobi-equation viscosity-solutions






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      edited Dec 10 at 9:14









      Harry49

      5,99121031




      5,99121031










      asked Dec 9 at 9:58









      Sam Wong

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          1 Answer
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          Long comment: The Hamilton-Jacobi PDE is derived from a canonical transformation involving a type-2 generating function $u(t,x)$ which makes vanish the new Hamiltonian
          $K=H(u_x) + u_t$. Here, $H(p)=|p|^{2/3}$ is the original Hamiltonian.



          For convex Hamiltonians $H$ which grow faster than the identity, the unique continuous viscosity solution can be obtained via the Lax-Hopf formula
          $$
          u(t,x) = inf_{yin Bbb R} leftlbrace t L big(tfrac{x-y}{t}big) - cos yrightrbrace
          $$

          where the Lagrangian $L$ is the Legendre-Fenchel transform of $H$:
          $$
          L(q) = sup_{pinBbb R} lbrace qp - H(p)rbrace = frac{4}{27}|q|^3 .
          $$

          However, the Hamiltonian is nonconvex here, which invalidates the previous approach. One may have a look at this post for complements.






          share|cite|improve this answer























          • Hi Harry, if we want to determine the value of $u$ at $(2015,0)$, then shall we need to know the period? Or can $2015$ be regarded as a enough large time and so that $u$ vanishes at $(2015,0)$? Thank you:)
            – Sam Wong
            Dec 10 at 2:27










          • Thank you so much. It's clear to me now :)
            – Sam Wong
            Dec 10 at 9:21










          • Hi Harry. I checked your another post yesterday. Does your another post imply that $u(2018,0)=0$ since $u(n,0)$ is closed to $0$ when $nge 5$ by your another post? But my friend told me that $u(2018,0)=-1$. Is he wrong?
            – Sam Wong
            Dec 10 at 22:39










          • Thanks for your hint, I will reconsider this problem :)
            – Sam Wong
            Dec 11 at 10:08










          • Thank you so much:)
            – Sam Wong
            Dec 11 at 14:03











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          1 Answer
          1






          active

          oldest

          votes








          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          1














          Long comment: The Hamilton-Jacobi PDE is derived from a canonical transformation involving a type-2 generating function $u(t,x)$ which makes vanish the new Hamiltonian
          $K=H(u_x) + u_t$. Here, $H(p)=|p|^{2/3}$ is the original Hamiltonian.



          For convex Hamiltonians $H$ which grow faster than the identity, the unique continuous viscosity solution can be obtained via the Lax-Hopf formula
          $$
          u(t,x) = inf_{yin Bbb R} leftlbrace t L big(tfrac{x-y}{t}big) - cos yrightrbrace
          $$

          where the Lagrangian $L$ is the Legendre-Fenchel transform of $H$:
          $$
          L(q) = sup_{pinBbb R} lbrace qp - H(p)rbrace = frac{4}{27}|q|^3 .
          $$

          However, the Hamiltonian is nonconvex here, which invalidates the previous approach. One may have a look at this post for complements.






          share|cite|improve this answer























          • Hi Harry, if we want to determine the value of $u$ at $(2015,0)$, then shall we need to know the period? Or can $2015$ be regarded as a enough large time and so that $u$ vanishes at $(2015,0)$? Thank you:)
            – Sam Wong
            Dec 10 at 2:27










          • Thank you so much. It's clear to me now :)
            – Sam Wong
            Dec 10 at 9:21










          • Hi Harry. I checked your another post yesterday. Does your another post imply that $u(2018,0)=0$ since $u(n,0)$ is closed to $0$ when $nge 5$ by your another post? But my friend told me that $u(2018,0)=-1$. Is he wrong?
            – Sam Wong
            Dec 10 at 22:39










          • Thanks for your hint, I will reconsider this problem :)
            – Sam Wong
            Dec 11 at 10:08










          • Thank you so much:)
            – Sam Wong
            Dec 11 at 14:03
















          1














          Long comment: The Hamilton-Jacobi PDE is derived from a canonical transformation involving a type-2 generating function $u(t,x)$ which makes vanish the new Hamiltonian
          $K=H(u_x) + u_t$. Here, $H(p)=|p|^{2/3}$ is the original Hamiltonian.



          For convex Hamiltonians $H$ which grow faster than the identity, the unique continuous viscosity solution can be obtained via the Lax-Hopf formula
          $$
          u(t,x) = inf_{yin Bbb R} leftlbrace t L big(tfrac{x-y}{t}big) - cos yrightrbrace
          $$

          where the Lagrangian $L$ is the Legendre-Fenchel transform of $H$:
          $$
          L(q) = sup_{pinBbb R} lbrace qp - H(p)rbrace = frac{4}{27}|q|^3 .
          $$

          However, the Hamiltonian is nonconvex here, which invalidates the previous approach. One may have a look at this post for complements.






          share|cite|improve this answer























          • Hi Harry, if we want to determine the value of $u$ at $(2015,0)$, then shall we need to know the period? Or can $2015$ be regarded as a enough large time and so that $u$ vanishes at $(2015,0)$? Thank you:)
            – Sam Wong
            Dec 10 at 2:27










          • Thank you so much. It's clear to me now :)
            – Sam Wong
            Dec 10 at 9:21










          • Hi Harry. I checked your another post yesterday. Does your another post imply that $u(2018,0)=0$ since $u(n,0)$ is closed to $0$ when $nge 5$ by your another post? But my friend told me that $u(2018,0)=-1$. Is he wrong?
            – Sam Wong
            Dec 10 at 22:39










          • Thanks for your hint, I will reconsider this problem :)
            – Sam Wong
            Dec 11 at 10:08










          • Thank you so much:)
            – Sam Wong
            Dec 11 at 14:03














          1












          1








          1






          Long comment: The Hamilton-Jacobi PDE is derived from a canonical transformation involving a type-2 generating function $u(t,x)$ which makes vanish the new Hamiltonian
          $K=H(u_x) + u_t$. Here, $H(p)=|p|^{2/3}$ is the original Hamiltonian.



          For convex Hamiltonians $H$ which grow faster than the identity, the unique continuous viscosity solution can be obtained via the Lax-Hopf formula
          $$
          u(t,x) = inf_{yin Bbb R} leftlbrace t L big(tfrac{x-y}{t}big) - cos yrightrbrace
          $$

          where the Lagrangian $L$ is the Legendre-Fenchel transform of $H$:
          $$
          L(q) = sup_{pinBbb R} lbrace qp - H(p)rbrace = frac{4}{27}|q|^3 .
          $$

          However, the Hamiltonian is nonconvex here, which invalidates the previous approach. One may have a look at this post for complements.






          share|cite|improve this answer














          Long comment: The Hamilton-Jacobi PDE is derived from a canonical transformation involving a type-2 generating function $u(t,x)$ which makes vanish the new Hamiltonian
          $K=H(u_x) + u_t$. Here, $H(p)=|p|^{2/3}$ is the original Hamiltonian.



          For convex Hamiltonians $H$ which grow faster than the identity, the unique continuous viscosity solution can be obtained via the Lax-Hopf formula
          $$
          u(t,x) = inf_{yin Bbb R} leftlbrace t L big(tfrac{x-y}{t}big) - cos yrightrbrace
          $$

          where the Lagrangian $L$ is the Legendre-Fenchel transform of $H$:
          $$
          L(q) = sup_{pinBbb R} lbrace qp - H(p)rbrace = frac{4}{27}|q|^3 .
          $$

          However, the Hamiltonian is nonconvex here, which invalidates the previous approach. One may have a look at this post for complements.







          share|cite|improve this answer














          share|cite|improve this answer



          share|cite|improve this answer








          edited Dec 20 at 9:20

























          answered Dec 9 at 11:13









          Harry49

          5,99121031




          5,99121031












          • Hi Harry, if we want to determine the value of $u$ at $(2015,0)$, then shall we need to know the period? Or can $2015$ be regarded as a enough large time and so that $u$ vanishes at $(2015,0)$? Thank you:)
            – Sam Wong
            Dec 10 at 2:27










          • Thank you so much. It's clear to me now :)
            – Sam Wong
            Dec 10 at 9:21










          • Hi Harry. I checked your another post yesterday. Does your another post imply that $u(2018,0)=0$ since $u(n,0)$ is closed to $0$ when $nge 5$ by your another post? But my friend told me that $u(2018,0)=-1$. Is he wrong?
            – Sam Wong
            Dec 10 at 22:39










          • Thanks for your hint, I will reconsider this problem :)
            – Sam Wong
            Dec 11 at 10:08










          • Thank you so much:)
            – Sam Wong
            Dec 11 at 14:03


















          • Hi Harry, if we want to determine the value of $u$ at $(2015,0)$, then shall we need to know the period? Or can $2015$ be regarded as a enough large time and so that $u$ vanishes at $(2015,0)$? Thank you:)
            – Sam Wong
            Dec 10 at 2:27










          • Thank you so much. It's clear to me now :)
            – Sam Wong
            Dec 10 at 9:21










          • Hi Harry. I checked your another post yesterday. Does your another post imply that $u(2018,0)=0$ since $u(n,0)$ is closed to $0$ when $nge 5$ by your another post? But my friend told me that $u(2018,0)=-1$. Is he wrong?
            – Sam Wong
            Dec 10 at 22:39










          • Thanks for your hint, I will reconsider this problem :)
            – Sam Wong
            Dec 11 at 10:08










          • Thank you so much:)
            – Sam Wong
            Dec 11 at 14:03
















          Hi Harry, if we want to determine the value of $u$ at $(2015,0)$, then shall we need to know the period? Or can $2015$ be regarded as a enough large time and so that $u$ vanishes at $(2015,0)$? Thank you:)
          – Sam Wong
          Dec 10 at 2:27




          Hi Harry, if we want to determine the value of $u$ at $(2015,0)$, then shall we need to know the period? Or can $2015$ be regarded as a enough large time and so that $u$ vanishes at $(2015,0)$? Thank you:)
          – Sam Wong
          Dec 10 at 2:27












          Thank you so much. It's clear to me now :)
          – Sam Wong
          Dec 10 at 9:21




          Thank you so much. It's clear to me now :)
          – Sam Wong
          Dec 10 at 9:21












          Hi Harry. I checked your another post yesterday. Does your another post imply that $u(2018,0)=0$ since $u(n,0)$ is closed to $0$ when $nge 5$ by your another post? But my friend told me that $u(2018,0)=-1$. Is he wrong?
          – Sam Wong
          Dec 10 at 22:39




          Hi Harry. I checked your another post yesterday. Does your another post imply that $u(2018,0)=0$ since $u(n,0)$ is closed to $0$ when $nge 5$ by your another post? But my friend told me that $u(2018,0)=-1$. Is he wrong?
          – Sam Wong
          Dec 10 at 22:39












          Thanks for your hint, I will reconsider this problem :)
          – Sam Wong
          Dec 11 at 10:08




          Thanks for your hint, I will reconsider this problem :)
          – Sam Wong
          Dec 11 at 10:08












          Thank you so much:)
          – Sam Wong
          Dec 11 at 14:03




          Thank you so much:)
          – Sam Wong
          Dec 11 at 14:03


















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