A strict inequality for the minimisation of the Willmore functional under isoperimetric constraint

具有 prescribed isoperimetric ratio 的 Willmore flow

The Willmore flow with prescribed isoperimetric ratio

提出保持 isoperimetric ratio 的非局部 L^2-梯度流研究 Willmore energy，证明低能球形初始数据下长时间存在且收敛于 Helfrich immersion，避免了局部约束流的有限时间奇点。

A Reverse Isoperimetric Inequality and its Application to the Gradient Flow of the Helfrich Functional

We prove a quantitative reverse isoperimetric inequality for embedded surfaces with Willmore energy bounded away from $8π$. We use this result to analyze the negative $L^2$ gradient flow of the Willmore energy plus a positive multiple of the inclosed volume. We show that initial surfaces of Willmore energy less than $8π$ with positive inclosed volume converge to a round point in finite or infinite time.

Helfrich's Energy and Constrained Minimisation

For every $g\in\mathbb{N}_0$ and $ε>0$, we construct a smooth genus $g$ surface embedded into the unit ball with area $8π$ and Willmore energy smaller than $8π+ ε$. From this we deduce that a minimising sequence for Willmore's energy in the class of genus $g$ surfaces embedded in the unit ball with area $8π$ converges to a doubly covered sphere for all $g\in\mathbb{N}_0$. We obtain the same result for certain Canham-Helfrich energies with $χ_K\leq 0$ without genus constraint and show that Canham-Helfrich energies with $χ_K>0$ are not bounded from below in the class of smooth surfaces with area…

加权流形中闭超曲面的Willmore型不等式

Willmore-type inequalities for closed hypersurfaces in weighted manifolds

该研究针对具非负Bakry-Émery里奇曲率的加权流形闭超曲面，推导稳态与收缩梯度Ricci孤立子中的精确Willmore型不等式并刻画等号情形，得到相关经典不等式的加权版本，还推出加权等周型不等式。

On the Uniqueness of Clifford Torus with Prescribed Isoperimetric Ratio

The Marques-Neves theorem asserts that among all the torodial (i.e. genus 1) closed surfaces, the Clifford torus has the minimal Willmore energy $\int H^2 \, dA$. % It is a natural conjecture that if one prescribes the isoperimetric Since the Willmore energy is invariant M{ö}bius transformations, it can be shown that there is a one-parameter family, up to homotheties, of genus 1 Willmore minimizers. It is then a natural conjecture that such a minimizer is unique if one prescribes its isoperimetric ratio. In this article, we show that this conjecture can be reduced to the positivity question of…

Analysis of the Inhomogeneous Willmore Equation

We study a class of fourth-order geometric problems modelling Willmore surfaces, conformally constrained Willmore surfaces, isoperimetrically constrained Willmore surfaces, bi-harmonic surfaces in the sense of Chen, among others. We prove several local energy estimates and derive a global gap lemma.

The isoperimetric problem for Lens spaces

We solve the isoperimetric problem in the Lens spaces with large fundamental group. Namely, we prove that the isoperimetric surfaces are geodesic spheres or tori of revolution about geodesics. We also show that the isoperimetric problem in L(3,1) and L(3,2) follows from the proof of the Willmore conjecture by Marques and Neves.

Surfaces of revolution in the Heisenberg group and the spectral generalization of the Willmore functional

We study the generalization of the Willmore functional for surfaces in the three-Heisenberg group. Its construction is based on the spectral theory of the Dirac operator coming to the Weierstrass representation of surfaces (see math.DG/0503707). By using surfaces of revolution we demonstrate that it resembles the Willmore functional for surfaces in the Euclidean space in many geometrical respects. We also observe the relation of these functionals to the isoperimetric problem.

加权中间里奇曲率下界下的Fenchel-Willmore-Chen不等式

Fenchel-Willmore-Chen inequality under lower bounds on weighted intermediate Ricci curvature

针对具1-Bakry-Émery k-里奇曲率下界的光滑度量测度空间，建立Fenchel-Willmore-Chen不等式并给出统一证明，同时证明非负1-加权里奇曲率的Sobolev与等周不等式。

On the Canham Problem: Bending Energy Minimizers for any Genus and Isoperimetric Ratio

Building on work of Mondino-Scharrer, we show that among closed, smoothly embedded surfaces in $\mathbb{R}^3$ of genus $g$ and given isoperimetric ratio $v$, there exists one with minimum bending energy $\mathcal{W}$. We do this by gluing $g+1$ small catenoidal bridges to the bigraph of a singular solution for the linearized Willmore equation $Δ(Δ+2)φ=0$ on the $(g+1)$-punctured sphere $\mathbb{S}^2$ to construct a comparison surface of genus $g$ with arbitrarily small isoperimetric ratio $v\in (0, 1)$ and $\mathcal{W} < 8π$.

Minimising a relaxed Willmore functional for graphs subject to boundary conditions

For a bounded smooth domain in the plane and smooth boundary data we consider the minimisation of the Willmore functional for graphs subject to Dirichlet or Navier boundary conditions. For $H^2$-regular graphs we show that bounds for the Willmore energy imply area and diameter bounds. We then consider the $L^1$-lower semicontinuous relaxation of the Willmore functional, which is shown to be indeed its largest possible extension, and characterise properties of functions with finite relaxed energy. In particular, we deduce compactness and lower-bound estimates for energy-bounded sequences. The l…

Singularities of mean curvature flow and isoperimetric inequalities in H^3

In this article, by following the method in \cite{PT}, combining Willmore energy with isoperimetric inequalities, we construct two examples of singularities under mean curvature flow in $\mathbb{H}^3$. More precisely, there exists a torus, which must develop a singularity under MCF before the volume it encloses decreases to zero. There also exists a topological sphere in the shape of a dumbbell, which must develop a singularity in the flow before its area shrinks to zero. Simultaneously, by using the flow, we proved an isoperimetric inequality for some domains in $\mathbb{H}^3$.