Daiane Iglesia Dolci
Verified @gmail.com
Scopus Publications
- An Adjoint-Based Methodology for Sensitivity Analysis of Time-Periodic Flows With Reduced Time Integration
Tomás Sambiase Privato, João de Sá Brasil Lima, Daiane Iglesia Dolci, Bruno Souza Carmo, Marcelo Tanaka Hayashi, Ernani Vitillo Volpe
International Journal for Numerical Methods in Engineering, 2025
Sensitivity analysis plays a vital role in understanding the impact of control parameter variations on system output, particularly in cases where an objective functional evaluates the output's merit. The adjoint method has gained popularity due to its efficient computation, especially when dealing with a large number of control parameters and a few functionals. While the discrete form of the adjoint method is prevalent, exploring its continuous counterpart can offer valuable insights into the underlying mathematical problem, particularly in characterizing the boundary conditions. This paper presents an investigation into the continuous form of the adjoint method applied to time‐dependent viscous flows, where the time dependence is either imposed by boundary conditions or arises from the system dynamics itself. The proposed approach enables the computation of sensitivities with respect to both geometric and operational control parameters using the same adjoint solution. For time‐periodic flows, a special formulation is developed to mitigate the computational costs associated with time integration. Results demonstrate that the methodology proposed in a previous work can be successfully extended to time‐dependent flows with fixed time spans. In such applications, time‐accurate simulations of physics and adjoint fields are sufficient. However, periodic flows necessitate the application of the Leibniz Rule because the period might depend on the control parameters, which introduces additional terms to the adjoint‐based sensitivity gradient. In that case, time integration can be limited to a minimum common multiple of all appearing periods in the flow. Although the accurate estimation of such multiple poses a challenge, the approach promises significant benefits for sensitivity analysis of fully established periodic flows. It leads to substantial cuts in computational costs and avoids transient data contamination. - Velocity model-based adapted meshes using optimal transport
Thiago Dias dos Santos, Alexandre Olender, Daiane Iglesia Dolci, Bruno Souza Carmo
Geophysics, 2024
In geophysical numerical models using the finite-element method or its variant, the spectral-element method, to solve seismic wave equations, a mesh is used to discretize the domain. Generating or adapting a mesh to complex geologic properties is a challenging task. To tackle this challenge, we develop an r-adaptivity method to generate or adapt a 2D mesh to a seismic velocity field. Our scheme relies on the optimal transport theory to perform vertices relocation, which generates good-shaped meshes and prevents tangled elements. The mesh adaptation can delineate different regions of interest, such as sharp interfaces, salt bodies, and discontinuities. The algorithm has a few user-defined parameters that control the mesh density. With typical seismic velocity examples (e.g., Camembert, SEAM Phase, and Marmousi-2), mesh adaptation capability is illustrated in meshes with triangular and quadrilateral elements, commonly used in seismic codes. In addition to its potential use in mesh generation, the method developed can be embedded in seismic inversion workflows such as multiscale full-waveform inversion to adapt the mesh to the field being inverted without incurring the input-output cost of remeshing and load rebalancing in parallel computations. The method can be extended to 3D meshes. - Effectiveness and computational efficiency of absorbing boundary conditions for full-waveform inversion
Daiane Iglesia Dolci, Felipe A. G. Silva, Pedro S. Peixoto, Ernani V. Volpe
Geoscientific Model Development, 2022
Full-waveform inversion (FWI) is a high-resolution numerical technique for seismic waves used to estimate the physical characteristics of a subsurface region. The continuous problem involves solving an inverse problem on an infinite domain, which is impractical from a computational perspective. In limited area models, absorbing boundary conditions (ABCs) are usually imposed to avoid wave reflections. Several relevant ABCs have been proposed, with extensive literature on their effectiveness on the direct wave problem. Here, we investigate and compare the theoretical and computational characteristics of several ABCs in the full inverse problem. After a brief review of the most widely used ABCs, we derive their formulations in their respective adjoint problems. The different ABCs are implemented in a highly optimized domain-specific language (DSL) computational framework, Devito, which is primarily used for seismic modelling problems. We evaluate the effectiveness, computational efficiency, and memory requirements of the ABC methods, considering from simple models to realistic ones. Our findings reveal that, even though the popular perfectly matching layers (PMLs) are effective at avoiding wave reflections at the boundaries, they can be computationally more demanding than less used hybrid ABCs. We show here that a proposed hybrid ABC formulation, with nested Higdon's boundary conditions, is the most cost-effective method among the methods considered here, for being as effective as or more effective than PML and other schemes but also for being computationally more efficient. - Sensitivity of the least stable modes to passive control for a flow around an elastically mounted circular cylinder
Daiane Iglesia Dolci, Bruno Souza Carmo
Physical Review Fluids, 2022
In this paper, a methodology to calculate the sensitivity of the least stable modes of fluidstructure interaction systems with respect to local forces is presented. We make use of the adjoint equations of the flow-structure coupled system to calculate the gradients, and the algorithms were implemented using the spectral/hp element method for the spatial discretization. The methodology was applied to two-dimensional incompressible laminar steady flows around an elastically-mounted circular cylinder, and we obtained the gradients of the real and imaginary parts of the least stable eigenvalues with respect to forces located at arbitrary points in the flow domain. Selected values of mass ratio and reduced velocity were considered in the simulations, and the results were compared to those obtained for a fixed cylinder at the same Reynolds number. We noticed that the sensitivity fields of the fluid-structure interaction system can be very different from its fixed structure counterpart, and amongst the cases, with an elastic structure, the fields vary greatly according to the reduced velocity. Finally, the sensitivity results were verified against linear and nonlinear simulations of flows with small control cylinders placed at locations selected according to the sensitivity fields. The agreement between the predictions made with the sensitivity analyses and the linear and nonlinear results of the forced flows was excellent. In some cases, it was possible to completely suppress the cylinder vibration. - Adjoint sensitivity analysis of steady laminar flows with respect to nongeometrical parameters
Daiane I. Dolci, João Sá Brasil Lima, Tomas S. Privato, Bruno S. Carmo, Ernani V. Volpe
International Journal for Numerical Methods in Engineering, 2021
Abstract This work explores an alternative approach to computing sensitivity (derivatives) of functionals with respect to a broader range of control parameters in fluid flow problems. It builds upon the complementary character of the boundary problems that underlie the flow and the corresponding adjoint equations. Such complementarity is used to ensure well‐posedness of the latter, which then yields a solution that conveys information on a broad range of sensitivities. This formulation of the boundary problem can extend the range of applications of the adjoint method to a host of new possibilities. The methodology is applied to internal and external laminar steady flows and the results are compared to those obtained with a finite‐difference approach. Good agreement is observed in all cases, which demonstrates the correctness and applicability of the method. - FWI performance improvement with the use of wavelet transforms
S. Malvar, D.I. Dolci, B.S. Carmo
1st Eage Digital Subsurface Conference in Latin America, 2021 - An Approach for optimizing the performance of an FWI Application on HPC Clusters
J.F.D. Souza, F.A.G. Da Silva, D.I. Dolci, L.R. Manrique, E.S. Gomi, H. Senger
1st Eage Digital Subsurface Conference in Latin America, 2021 - Bifurcation analysis of the primary instability in the flow around a flexibly mounted circular cylinder
Daiane I. Dolci, Bruno S. Carmo
Journal of Fluid Mechanics, 2019
The nonlinear character of the primary bifurcation is investigated for the flow around a flexibly mounted circular cylinder. We have considered the cases in which the cylinder can oscillate in the transverse direction only and in both transverse and in-line directions. Low and high values of mass ratio ($m^{\\ast }=5$ and 50) were studied, and reduced velocity ($V_{r}$) values are chosen inside ($V_{r}=9$) and outside ($V_{r}=5$ and $V_{r}=13$) the lock-in range for low Reynolds numbers. For each combination of $m^{\\ast }$ and $V_{r}$, a global linear stability analysis was applied to find the critical Reynolds number $Re_{c}$ of the fluid–structure system. For $V_{r}$ in the lock-in range, the values of $Re_{c}$ were noticeably less than the critical Reynolds number of the flow around a fixed circular cylinder ($Re_{c_{0}}\\cong 47$). On the other hand, for $V_{r}$ outside the lock-in range, the values of $Re_{c}$ were close to $Re_{c_{0}}$. Next, nonlinear analyses were performed in the vicinity of $Re_{c}$ for each case. Subcritical character (with hysteresis) was observed for $V_{r}$ in the lock-in range, while for $V_{r}$ outside the lock-in region the bifurcations were found to be supercritical (without hysteresis). This shows that when the coupling between the structure and flow is strong, due to the proximity of the natural frequencies of the isolated systems, it significantly changes both the linear and nonlinear responses observed. - Numerical predictions of viscoelastic flows with an algebraic extra-stress model
11th World Congress on Computational Mechanics Wccm 2014 5th European Conference on Computational Mechanics Eccm 2014 and 6th European Conference on Computational Fluid Dynamics Ecfd 2014, 2014
