Trouble calculating the Laplace-Beltrami operator through this formula












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Let $U$ be an open, bounded and connected subset of $mathbb R^3$ with a $C^2−$regular boundary $partial U$. For an arbitary $x_0 in partial U$ define the function $f:B(x_0,r) cap partial U to mathbb R$ as follows: $f(x)=C|x−x_0|^2$. I'm interested in computing $Δf$ where $Δ$ denotes the Laplace-Beltrami operator.



After some research (since I'm not familiar to the Laplace-Beltrami operator) I found this formula:




$Delta f= {Delta}_{mathbb R^2} f-{nabla}_{mathbb
R^2}^2f(eta,eta)+H{nabla}_{mathbb R^2}f$




where $Δ_{mathbb R^2}$ denotes the usual Laplace operator, $H$ is the mean curvature vector over $partial U$ and $eta$ is a unit normal vector field.



How do I compute the Hessian term ${nabla}_{mathbb R^2}^2f(eta,eta)$?



DISCLAIMER: I've only seen an introduction to differential geometry on manifolds in the past so maybe my question is too elementary



I would appreciate any help.



Thanks in advance!










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    Let $U$ be an open, bounded and connected subset of $mathbb R^3$ with a $C^2−$regular boundary $partial U$. For an arbitary $x_0 in partial U$ define the function $f:B(x_0,r) cap partial U to mathbb R$ as follows: $f(x)=C|x−x_0|^2$. I'm interested in computing $Δf$ where $Δ$ denotes the Laplace-Beltrami operator.



    After some research (since I'm not familiar to the Laplace-Beltrami operator) I found this formula:




    $Delta f= {Delta}_{mathbb R^2} f-{nabla}_{mathbb
    R^2}^2f(eta,eta)+H{nabla}_{mathbb R^2}f$




    where $Δ_{mathbb R^2}$ denotes the usual Laplace operator, $H$ is the mean curvature vector over $partial U$ and $eta$ is a unit normal vector field.



    How do I compute the Hessian term ${nabla}_{mathbb R^2}^2f(eta,eta)$?



    DISCLAIMER: I've only seen an introduction to differential geometry on manifolds in the past so maybe my question is too elementary



    I would appreciate any help.



    Thanks in advance!










    share|cite|improve this question



























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      0


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      Let $U$ be an open, bounded and connected subset of $mathbb R^3$ with a $C^2−$regular boundary $partial U$. For an arbitary $x_0 in partial U$ define the function $f:B(x_0,r) cap partial U to mathbb R$ as follows: $f(x)=C|x−x_0|^2$. I'm interested in computing $Δf$ where $Δ$ denotes the Laplace-Beltrami operator.



      After some research (since I'm not familiar to the Laplace-Beltrami operator) I found this formula:




      $Delta f= {Delta}_{mathbb R^2} f-{nabla}_{mathbb
      R^2}^2f(eta,eta)+H{nabla}_{mathbb R^2}f$




      where $Δ_{mathbb R^2}$ denotes the usual Laplace operator, $H$ is the mean curvature vector over $partial U$ and $eta$ is a unit normal vector field.



      How do I compute the Hessian term ${nabla}_{mathbb R^2}^2f(eta,eta)$?



      DISCLAIMER: I've only seen an introduction to differential geometry on manifolds in the past so maybe my question is too elementary



      I would appreciate any help.



      Thanks in advance!










      share|cite|improve this question















      Let $U$ be an open, bounded and connected subset of $mathbb R^3$ with a $C^2−$regular boundary $partial U$. For an arbitary $x_0 in partial U$ define the function $f:B(x_0,r) cap partial U to mathbb R$ as follows: $f(x)=C|x−x_0|^2$. I'm interested in computing $Δf$ where $Δ$ denotes the Laplace-Beltrami operator.



      After some research (since I'm not familiar to the Laplace-Beltrami operator) I found this formula:




      $Delta f= {Delta}_{mathbb R^2} f-{nabla}_{mathbb
      R^2}^2f(eta,eta)+H{nabla}_{mathbb R^2}f$




      where $Δ_{mathbb R^2}$ denotes the usual Laplace operator, $H$ is the mean curvature vector over $partial U$ and $eta$ is a unit normal vector field.



      How do I compute the Hessian term ${nabla}_{mathbb R^2}^2f(eta,eta)$?



      DISCLAIMER: I've only seen an introduction to differential geometry on manifolds in the past so maybe my question is too elementary



      I would appreciate any help.



      Thanks in advance!







      analysis multivariable-calculus differential-geometry laplacian hessian-matrix






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      edited Dec 13 '18 at 11:22







      kaithkolesidou

















      asked Dec 13 '18 at 10:05









      kaithkolesidoukaithkolesidou

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