Seminars held in Chile related to this course:
- Robust shape optimization with small uncertainties
- Body-fitted topology optimization of 2D and 3D fluid-to-fluid heat exchangers
Robust shape optimization with small uncertainties
December 21, 2022 – 10:30 hrs.
Abstract: In this talk, we propose two approaches for dealing with small uncertainties in geometry and topology optimization of structures. Uncertainties occur in the loadings, the material properties, the geometry or the imposed vibration frequency. A first approach, in a worst-case scenario, amounts to linearize the considered cost function with respect to the uncertain parameters, then to consider the supremum function of the obtained linear approximation, which can be rewritten as a more `classical’ function of the design, owing to standard adjoint techniques from optimal control theory. The resulting `linearized worst-case’ objective function turns out to be the sum of the initial cost functionand of a norm of an adjoint state function, which is dual with respect to the considered norm over perturbations.
A second approach considers objective functions which are mean values, variances or failure probabilities of standard cost functions under random uncertainties. By assuming that the uncertainties are small and generated by a finite number $N$ of random variables, and using first- or second-order Taylor expansions, we propose a deterministic approach to optimize approximate objective functions. The computational cost is similar to that of a multiple load problems where the number of loads is $N$.
We demonstrate the effectiveness of both approaches on various parametric and geometric optimization problems for elastic structures in two space dimensions.
The talk is based on joint work with Charles Dapogny (LJK, Grenoble).
Zoom link:
https://reuna.zoom.us/j/5185702306?pwd=cEtaeGVqUk1ZY0lkQ2Z0WU4yNlFmUT09
Venue:
Sala de Seminarios John Von Neumann, Centro de Modelamiento Matemático (Beauchef 851, Edificio Norte, Piso 7)
Body-fitted topology optimization of 2D and 3D fluid-to-fluid heat exchangers
December 12, 2022
Abstract:
Body-fitted topology optimization of 2D and 3D fluid-to-fluid heat exchangers
G. Allaire, C. Dapogny, F. Feppon, P. Jolivet
This talk is concerned with a topology optimization approach for the design of fluid-to-fluid heat exchangers which rests on an explicit meshed discretization of the solid and fluid phases, at every iteration of the optimization process.
The considered physical situations involve a weak coupling between the Navier–Stokes equations for the velocity and the pressure in the fluid, and the convection–diffusion equation for the temperature field.
The proposed framework combines several recent techniques from the field of shape and topology optimization, and notably a level-set based mesh evolution algorithm for tracking shapes and their deformations, an efficient optimization algorithm for constrained shape optimization problems, and a numerical method to handle a wide variety of geometric constraints such as thickness constraints and non-penetration constraints.
Our strategy is applied to the optimization of various types of heat exchangers. An example is the design of 2D and 3D heat exchangers composed of two types of fluid channels (hot and cold), which are separated by a solid body. A non-mixing constraint between the fluid components containing the hot and cold phases is enforced by prescribing a minimum distance between them.
Our numerical results demonstrate the efficiency of our approach in generating new, realistic, and unconventional heat exchanger designs.
Venue:
Pontificia Universidad Católica de Chile, Santiago