SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "hsv:(NATURVETENSKAP) hsv:(Matematik) hsv:(Beräkningsmatematik) ;pers:(Larson Mats G)"

Sökning: hsv:(NATURVETENSKAP) hsv:(Matematik) hsv:(Beräkningsmatematik) > Larson Mats G

  • Resultat 1-10 av 125
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Elfverson, Daniel, et al. (författare)
  • Multiscale methods for problems with complex geometry
  • 2017
  • Ingår i: Computer Methods in Applied Mechanics and Engineering. - : Elsevier BV. - 0045-7825 .- 1879-2138. ; 321, s. 103-123
  • Tidskriftsartikel (refereegranskat)abstract
    • We propose a multiscale method for elliptic problems on complex domains, e.g. domains with cracks or complicated boundary. For local singularities this paper also offers a discrete alternative to enrichment techniques such as XFEM. We construct corrected coarse test and trail spaces which takes the fine scale features of the computational domain into account. The corrections only need to be computed in regions surrounding fine scale geometric features. We achieve linear convergence rate in the energy norm for the multiscale solution. Moreover, the conditioning of the resulting matrices is not affected by the way the domain boundary cuts the coarse elements in the background mesh. The analytical findings are verified in a series of numerical experiments.
  •  
2.
  • Burman, Erik, et al. (författare)
  • CutFEM based on extended finite element spaces
  • 2022
  • Ingår i: Numerische Mathematik. - : Springer. - 0029-599X .- 0945-3245. ; 152, s. 331-369
  • Tidskriftsartikel (refereegranskat)abstract
    • We develop a general framework for construction and analysis of discrete extension operators with application to unfitted finite element approximation of partial differential equations. In unfitted methods so called cut elements intersected by the boundary occur and these elements must in general by stabilized in some way. Discrete extension operators provides such a stabilization by modification of the finite element space close to the boundary. More, precisely the finite element space is extended from the stable interior elements over the boundary in a stable way which also guarantees optimal approximation properties. Our framework is applicable to all standard nodal based finite elements of various order and regularity. We develop an abstract theory for elliptic problems and associated parabolic time dependent partial differential equations and derive a priori error estimates. We finally apply this to some examples of partial differential equations of different order including the interface problems, the biharmonic operator and the sixth order triharmonic operator.
  •  
3.
  • Burman, Erik, et al. (författare)
  • Low regularity estimates for CutFEM approximations of an elliptic problem with mixed boundary conditions
  • 2024
  • Ingår i: Mathematics of Computation. - : American Mathematical Society (AMS). - 0025-5718 .- 1088-6842. ; 93:345, s. 35-54
  • Tidskriftsartikel (refereegranskat)abstract
    • We show error estimates for a cut finite element approximation of a second order elliptic problem with mixed boundary conditions. The error estimates are of low regularity type where we consider the case when the exact solution u ∈ Hs with s ∈ (1, 3/2]. For Nitsche type methods this case requires special handling of the terms involving the normal flux of the exact solution at the the boundary. For Dirichlet boundary conditions the estimates are optimal, whereas in the case of mixed Dirichlet-Neumann boundary conditions they are suboptimal by a logarithmic factor.
  •  
4.
  • Hansbo, Peter, et al. (författare)
  • STABILIZED FINITE ELEMENT APPROXIMATION OF THE MEAN CURVATURE VECTOR ON CLOSED SURFACES
  • 2015
  • Ingår i: SIAM Journal on Numerical Analysis. - : Society for Industrial and Applied Mathematics. - 0036-1429 .- 1095-7170. ; 53:4, s. 1806-1832
  • Tidskriftsartikel (refereegranskat)abstract
    • The mean curvature vector of a surface is obtained by letting the Laplace-Beltrami operator act on the embedding of the surface in R-3. In this contribution we develop a stabilized finite element approximation of the mean curvature vector of certain piecewise linear surfaces which enjoys first order convergence in L-2. The stabilization involves the jump in the tangent gradient in the direction of the outer co-normals at each edge in the surface mesh. We consider both standard meshed surfaces and so-called cut surfaces that are level sets of piecewise linear distance functions. We prove a priori error estimates and verify the theoretical results numerically.
  •  
5.
  • Hansbo, Peter, et al. (författare)
  • A simple nonconforming tetrahedral element for the Stokes equations
  • 2022
  • Ingår i: Computer Methods in Applied Mechanics and Engineering. - : Elsevier. - 0045-7825 .- 1879-2138. ; 400
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper we apply a nonconforming rotated bilinear tetrahedral element to the Stokes problem in R3. We show that the element is stable in combination with a piecewise linear, continuous, approximation of the pressure. This gives an approximation similar to the well known continuous P2–P1 Taylor–Hood element, but with fewer degrees of freedom. The element is a stable non-conforming low order element which fulfils Korn's inequality, leading to stability also in the case where the Stokes equations are written on stress form for use in the case of free surface flow.
  •  
6.
  • Bensow, Rickard, 1972, et al. (författare)
  • Residual Based VMS Subgrid Modeling for Vortex Flows
  • 2009
  • Ingår i: Computer Methods in Applied Mechanics and Engineering. - : Elsevier BV. - 0045-7825 .- 1879-2138. ; 199:13-16, s. 802-809
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper presents a residual based subgrid modeling approach for Large Eddy Simulations (LES) based on the variational multiscale method as a cure for the problem of preservation of vortices in numerical flow simulation. This approach combines a splitting of the non-linear term in the Navier–Stokes equations into strain and vorticity with a residual based modeling of the subgrid problems. The benefit is that certain driving phenomena, normally not present in subgrid modeling, e.g. vortex stretching, can be seen in the equations.Here, we focus on two of the subgrid terms arising from the subgrid scale problem. The effect of the two terms are illustrated in an LES of a three dimensional flow around a wing where the main feature is the formation and preservation of a tip vortex, an important phenomenon in many aerodynamic and hydrodynamical applications. We see that the addition of the new subgrid terms correctly counteracts the dissipative effect, arising from numerics and turbulence modeling, on the vortex and thus strongly improves prediction of the tip vortex.
  •  
7.
  • Burman, Erik, et al. (författare)
  • A stabilized cut finite element method for partial differential equations on surfaces : The Laplace-Beltrami operator
  • 2015
  • Ingår i: Computer Methods in Applied Mechanics and Engineering. - : Elsevier BV. - 0045-7825 .- 1879-2138. ; 285, s. 188-207
  • Tidskriftsartikel (refereegranskat)abstract
    • We consider solving the Laplace-Beltrami problem on a smooth two dimensional surface embedded into a three dimensional space meshed with tetrahedra. The mesh does not respect the surface and thus the surface cuts through the elements. We consider a Galerkin method based on using the restrictions of continuous piecewise linears defined on the tetrahedra to the surface as trial and test functions. The resulting discrete method may be severely ill-conditioned, and the main purpose of this paper is to suggest a remedy for this problem based on adding a consistent stabilization term to the original bilinear form. We show optimal estimates for the condition number of the stabilized method independent of the location of the surface. We also prove optimal a priori error estimates for the stabilized method. (c) 2014 Elsevier B.V. All rights reserved.
  •  
8.
  • Burman, Erik, et al. (författare)
  • A stabilized cut streamline diffusion finite element method for convection–diffusion problems on surfaces
  • 2020
  • Ingår i: Computer Methods in Applied Mechanics and Engineering. - : Elsevier. - 0045-7825 .- 1879-2138. ; 358
  • Tidskriftsartikel (refereegranskat)abstract
    • We develop a stabilized cut finite element method for the stationary convection–diffusion problem on a surface embedded in Rd. The cut finite element method is based on using an embedding of the surface into a three dimensional mesh consisting of tetrahedra and then using the restriction of the standard piecewise linear continuous elements to a piecewise linear approximation of the surface. The stabilization consists of a standard streamline diffusion stabilization term on the discrete surface and a so called normal gradient stabilization term on the full tetrahedral elements in the active mesh. We prove optimal order a priori error estimates in the standard norm associated with the streamline diffusion method and bounds for the condition number of the resulting stiffness matrix. The condition number is of optimal order for a specific choice of method parameters. Numerical examples supporting our theoretical results are also included. 
  •  
9.
  • Burman, E., et al. (författare)
  • Augmented Lagrangian Method for Thin Plates with Signorini Boundaries
  • 2021
  • Ingår i: Numerical Mathematics and Advanced Applications ENUMATH 2019. - Cham : Springer. - 9783030558734 - 9783030558741 - 9783030558765 ; , s. 509-519
  • Konferensbidrag (refereegranskat)abstract
    • We consider C1-continuous approximations of the Kirchhoff plate problem in combination with a mesh dependent augmented Lagrangian method on a simply supported Signorini boundary.
  •  
10.
  • Burman, Erik, et al. (författare)
  • Cut Bogner-Fox-Schmit elements for plates
  • 2020
  • Ingår i: Advanced Modeling and Simulation in Engineering Sciences. - : Springer. - 2213-7467. ; 7:1
  • Tidskriftsartikel (refereegranskat)abstract
    • We present and analyze a method for thin plates based on cut Bogner-Fox-Schmit elements, which are C1 elements obtained by taking tensor products of Hermite splines. The formulation is based on Nitsche’s method for weak enforcement of essential boundary conditions together with addition of certain stabilization terms that enable us to establish coercivity and stability of the resulting system of linear equations. We also take geometric approximation of the boundary into account and we focus our presentation on the simply supported boundary conditions which is the most sensitive case for geometric approximation of the boundary. 
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-10 av 125
Typ av publikation
tidskriftsartikel (100)
konferensbidrag (10)
annan publikation (6)
doktorsavhandling (5)
rapport (1)
forskningsöversikt (1)
visa fler...
bokkapitel (1)
licentiatavhandling (1)
visa färre...
Typ av innehåll
refereegranskat (110)
övrigt vetenskapligt/konstnärligt (15)
Författare/redaktör
Larson, Mats G. (105)
Hansbo, Peter (56)
Burman, Erik (32)
Larsson, Karl, 1981- (24)
Larson, Mats G, 1968 (14)
Logg, Anders, 1976 (10)
visa fler...
Massing, André (9)
Hansbo, Peter F G, 1 ... (8)
Elfverson, Daniel (7)
Zahedi, Sara (7)
Hansbo, Peter, 1959- (7)
Larson, Mats G., Pro ... (6)
Burman, E. (5)
Bensow, Rickard, 197 ... (4)
Zahedi, Sara, 1981- (4)
Johansson, August (3)
Cenanovic, Mirza (3)
Massing, André, 1977 ... (3)
Johansson, August, 1 ... (3)
Rognes, Marie E. (2)
Jonsson, Tobias (2)
Kvamsdal, Trond (2)
Claus, Susanne (2)
He, Cuiyu (2)
Carey, V. (2)
Estep, D. (2)
Tavener, S. (2)
Johansson, A (1)
Larsson, Fredrik, 19 ... (1)
Klarbring, Anders (1)
Wadbro, Eddie, 1981- (1)
Vesterlund, Per (1)
Araujo-Cabarcas, Jua ... (1)
Engström, Christian, ... (1)
Cohen, David, Docent ... (1)
Ovall, Jeffrey, Prof ... (1)
Söderlund, Robert (1)
Persson, Lennart, Pr ... (1)
Oksanen, Lauri (1)
Stenberg, Rolf (1)
Bengzon, Fredrik, 19 ... (1)
Söderlund, Robert, 1 ... (1)
Björklund, Martin (1)
Boiveau, Thomas (1)
Lundholm, Carl, 1987 (1)
Kreiss, Gunilla, Pro ... (1)
Samvin, David (1)
Larsson, Karl (1)
Burman, Erik N. (1)
Ginting, V. (1)
visa färre...
Lärosäte
Umeå universitet (113)
Jönköping University (65)
Chalmers tekniska högskola (28)
Göteborgs universitet (18)
Kungliga Tekniska Högskolan (10)
Uppsala universitet (10)
visa fler...
Linköpings universitet (1)
Karlstads universitet (1)
visa färre...
Språk
Engelska (125)
Forskningsämne (UKÄ/SCB)
Naturvetenskap (125)
Teknik (28)

År

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy