论文标题

Fenics和Firedrake的瞬态PDE的自动形状衍生物

Automatic shape derivatives for transient PDEs in FEniCS and Firedrake

论文作者

Dokken, Jørgen S., Mitusch, Sebastian K., Funke, Simon W.

论文摘要

在行业中,当设计飞机,汽车和涡轮机等结构时,形状优化问题至关重要。对于许多这些应用程序,结构随时间变化,有规定的或非规定的运动。因此,在优化结构设计时,在模拟中捕获这些特征很重要。使用基于梯度的算法,手动得出形状衍生物可能会变得非常复杂和误差,尤其是在时间依赖性的非线性偏微分方程的情况下。为了减轻这种负担,我们提出了一个高级算法分化工具,该工具将自动计算有限元框架fenics和firedrake中偏微分方程的第一和二阶形状衍生物。使用伴随方法计算一阶形状衍生物,而使用切线线性方法和伴随方法的组合计算二阶形状衍生物。伴随和切线线性方程是针对任何变化形式序列的象征性得出的。结果,我们的方法可用于广泛的PDE问题,并且离散地一致。我们通过介绍几个示例来说明框架的一般性,这些示例涵盖了固定域和瞬态域的线性,非线性和时间依赖性PDE的范围。

In industry, shape optimization problems are of utter importance when designing structures such as aircraft, automobiles and turbines. For many of these applications, the structure changes over time, with a prescribed or non-prescribed movement. Therefore, it is important to capture these features in simulations when optimizing the design of the structure. Using gradient based algorithms, deriving the shape derivative manually can become very complex and error prone, especially in the case of time-dependent non-linear partial differential equations. To ease this burden, we present a high-level algorithmic differentiation tool that automatically computes first and second order shape derivatives for partial differential equations posed in the finite element frameworks FEniCS and Firedrake. The first order shape derivatives are computed using the adjoint method, while the second order shape derivatives are computed using a combination of the tangent linear method and the adjoint method. The adjoint and tangent linear equations are symbolically derived for any sequence of variational forms. As a consequence our methodology works for a wide range of PDE problems and is discretely consistent. We illustrate the generality of our framework by presenting several examples, spanning the range of linear, non-linear and time-dependent PDEs for both stationary and transient domains.

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