

JANNA CARLO
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(updated on 10/06/2018 11:46)
Proposals for thesis
1 High Performance Constraint Preconditioning for the Stokes Equations
The numerical solution to the Stokes flow equations is a central topic in several fields of application. The linearized linear system that arises from the PDE discretization is typically saddlepoint system, a tough problem from the numerical linear algebra perspective. Constraint precondtioners are known to be a powerful tool for this kind of problems, however their effective and scalable implementation on high performance systems is still an open problem. 2 Development of scalable algorithms for subsurface simulations on HPC systems Simulating subsurface processes is required in several fields from subsurface hydrology, to geotechnical engineering, from basin simulation to reservoir engineering. The main issue related to these kinds of simulation is usually the large size and heterogeneity of the physical domain that requires discretization involving a hugh number of equations. To this aim, supercomputers are becoming available to scientist and engineers with an increasing need of designing parallel algorithms to exploit these computational resources. 3 Algebraic Multigrid preconditioning for illconditioned structural problems The numerical solution to the Cauchy indefinite equilibrium equations is a typical task in civil and mechanical engineering, as well as in many other fields, with a large number of open and commercial software available to the end user. The arising linear systems may represent a serious bottleneck in the overall simulation process that may take more than the 90% of the total time. Algebraic Multigrid (AMG) techniques represent a powerful tool for the solution of linear systems, however they have been historically designed for scalar PDEs, such as e.g. the Poisson equation. For nonscalar PDEs arising in computational mechanics, AMG performance still needs to be improved. 4 Modelling channel network dynamics in tidal landscapes (Joint thesis with Prof. Andrea D'Alpaos, Dipartimento di Geoscienze) Tidal landscapes display sticking patterns emerging from the interaction of biogeomorphic processes over a wide range of spatial and temporal scales. Among these patterns, channel networks are key features of the tidal landscape, because they exert a strong control on hydrodynamics, sediment and nutrient dynamics within tidal systems. The morphodynamic model of network evolution is based on a simplified hydrodynamic model where, by assuming a balance between water surface gradients and friction, the 2D shallow water equations is simplified to a Poisson boundary value problem, whose numerical solution is obtained through a Finite Difference discretization. The accurate modeling of this physical process requires high resolution grids with the overall computational cost becoming an unavoidable limiting factor. The use of High Performance Computers may help overcome these difficulties allowing for large scale simulations in acceptable time. Curriculum Vitae
Carlo Janna graduated in Civil Engineering at the University of Padova in October 2nd, 2003 with 109 points over 110 and in the same University he got his PhD defending a thesis entitled "Numerical modeling of the mechanical behavior of regional faults in the geological sequestration of anthropogenic CO2 sequestration". Since December 2011 he is assistant professor at the Department ICEA. The main scientific interests concern on one hand the mathematical and numerical modeling of the mechanics of porous media in both saturated and unsaturated conditions with specific applications in subsurface hydrology and petroleum industry, on the other the numerical linear algebra. His main activity is the development and implementation of numerical models based on the Finite Element method for the simulation of subsurface coupled and uncoupled geomechanical and fluid dynamical processes in the exploitation of deep aquifer or reservoir resources. As to the linear algebra, Carlo Janna studies and develops numerical techniques for the solution of large sparse linear systems and eigenproblems and more specifically iterative methods and preconditioners. For sequential computers, he studied and developed several ad hoc preconditioners for the solution to specific problems arising in subsurface simulations. From 2010 to 2012, Carlo Janna joined the HPC research projects PARPSEA (PARallel Preconditioners for large Size Engineering Applications), SCALPREC (SCALable PREConditioners), OPTIDAS (OPTImization and Data ASSimilation) e SPREAD (Scalable PREconditioners for Advanced Discretizations) studying and developing new preconditioners for massively parallel computers.
Lecturer's Curriculum (PDF): D0D3F7F9A0BF1C81F2807B2AD6515E4F.pdf Research areas
1 Numerical Analysis
2 Numerical Linear Algebra 3 Parallel Computing 4 Geomechanis 5 Environmental modelling More specifically:  Theoretical study, development and implementation of “Constraint”preconditioners obtained by combining ILU and AINV preconditioners for the solution of illconditioned linear systems arising in contact mechanics problems;  Theoretical study, development and implementation of “Breakdownfree” multilevel preconditioners based on incomplete factorization with “Diagonal Shift” and second order correction for the efficient solution of illconditioned linear systems arising in the geomechanical modeling of faulted rocks;  Numerical study and experimentation of preconditioner update techniques for the parallel solution of shifted linear systems arising in transient problems of flow in a highly heterogeneous medium;  Theoretical study, development and implementation of hybrid preconditioners coupling FSAI and Incomplete Factorization on massively parallel computers;  Use of “Domain Decomposition” techniques and ordering strategies on hybrid FSAIILU preconditioners to improve their parallel performance on HPC systems;  Theoretical study, development and implementation of iterative methods coupled with hybrid preconditioners in the solution of eigenvalue problem on parallel computers;  Theoretical study, development and implementation of parallel “Constraint” preconditioners for fully coupled poroelastic problems;  Development and implementation of new algorithms for the computation of FSAI preconditioenrs on the new Graphical Proccessing Unit (GPU) hardware;  Theoretical study, development and implementation of adaptive AMG preconditioners for HPC systems;  Theoretical study, development and implementation of Interface Elements for the simulation of mechanical discontinuities within faulted porous media;  Theoretical study, development and implementation of nonlinear constitutive laws for the numerical simulation of porous materials;  Use of fully coupled and uncoupled poroelastic models on problems related to the development of natural resources in deep auifers or reservoirs and to the reinjection of CO2 or gas underground;  Complex geomechanical models calibration through the use of Data Assimilation and Optimization techniques. Publications
1. V. A. Paludetto Magri, A. Franceschini, M. Ferronato, and C. Janna (2018), Multilevel Approaches for FSAI Preconditioning, Numerical Linear Algebra with Applications, available online (SJRScopus 1.104).
2. S. Ye, A. Franceschini, Y. Zhang, C. Janna, X. Gong, J. Yu and P. Teatini (2018), Earth fissure development caused by extensive aquifer exploitation. A novel modelling approach applied to the Wuxi case study, China, Water Resources Research, 54, pp. 2249–2269 (SJRScopus 2.296). 3. H. T. Honorio, C. R. Maliska, M. Ferronato, and C. Janna (2018), A stabilized elementbased finite volume method for poroelastic problems, Journal of Computational Physics, 364, pp. 49–72 (SJRScopus 2.047). 4. Franceschini, V. A. Paludetto Magri, M. Ferronato, and C. Janna (2018), A Robust Multilevel Approximate Inverse Preconditioner for Symmetric Positive Definite Matrices, SIAM Journal on Matrix Analysis and Applications, 39, pp. 123–147 (SJRScopus 1.739). 5. N. Spiezia, M. Ferronato, C. Janna and P. Teatini (2017), A twoinvariant pseudoelastic model for reservoir compaction, International Journal for Numerical and Analytical Methods in Geomechanics, 41, pp. 1870–1893 (SJRScopus 1.452). 6. Zanette, M. Ferronato, and C. Janna (2017), Enriching the finite element method with meshfree techniques in structural mechanics, International Journal for Numerical Methods in Engineering, 110, pp. 675–700 (SJRScopus 1.623). 7. R. Baggio, A. Franceschini, N. Spiezia, and C. Janna (2017), Rigid body modes deflation of the preconditioned conjugate gradient in the solution of discretized structural problems, Computers & Structures, 18, pp. 15–26 (SJRScopus 1.630). 8. Franceschini, M. Ferronato, C. Janna, and P. Teatini (2016), A novel Lagrangian approach for a stable numerical simulation of fault and fracture mechanics, Journal of Computational Physics, 314, pp. 503–521 (SJRScopus 2.047). 9. M. Bernaschi, M. Bisson, C. Fantozzi, and C. Janna (2016), A FSAI preconditioned conjugate gradient solver on GPUs, SIAM Journal on Scientific Computing, 38, pp. C53–C72 (SJRScopus 1.973). 10. C. Janna, M. Ferronato and G. Gambolati (2015), The use of supernodes in factored sparse approximate inverse preconditioning, SIAM Journal on Scientific Computing, 37, pp. C72–C94 (SJRScopus 1.973). Lecturer's Publications (PDF): D0D3F7F9A0BF1C81F2807B2AD6515E4F.pdf List of taught course units in A.Y. 2018/19


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