# Dynaflow™

Description of Computer Code

Jean H. Prévost

Department of Civil and Environmental Engineering

Princeton University

Princeton, New Jersey 08544-5263

E-mail: prevost@princeton.edu

Dynaflow™ is a finite element analysis program for the static and transient response of linear and nonlinear two- and three-dimensional systems. In particular, it offers transient analysis capabilities for both parabolic and hyperbolic initial value problems in solid, structural and fluid mechanics. There are no restrictions on the number of elements, the number of load cases, the number of load-time functions, and the number or bandwidth of the equations. Despite large system capacity, no loss of efficiency is encountered in solving small problems. In both static and transient analyses, an implicit-explicit predictor-(multi)corrector scheme is used. The nonlinear implicit solution algorithms available include: successive substitutions, Newton-Raphson, modified Newton and quasi-Newton (BFGS and Broyden updates) iterations, with selective line search options. Some features which are available in the program include:

- Multi-field/physics analysis capabilities via selective specification of multiple solution staggers.
- Multi-staggered coupled solution analysis options.
- MPI implementation options to fully exploit the architecture of parallel computers.
- Domain decomposition options to partition equations for efficient processing on parallel computers.
- Selective element reordering options applicable to unstructured as well as structured meshes in order to allow parallel and/or vector processing of elemental arrays in blocks.
- Selective specification of high- and low-speed storage allocations options.
- Direct symmetric and non-symmetric matrix column equation solvers (in-core and out of-core Crout profile solvers). Symmetric frontal solver (in-core and/or out-of-core).
- Iterative matrix-free conjugate gradient and GMRES solution procedures.
- Eigenvalue/vector solution solvers including determinant search, subspace iterations and various Lanczos algorithms.
- Equation numbering optimization option to reduce bandwidth and column heights of stiffness matrix.
- Slave nodes, equivalence nodes and multi-node constraints capabilities.
- Selective specification of element-by-element implicit, explicit or implicit-explicit options.
- Selective specification of element-by-element reduced/selective integration options.
- Coupled field equation capabilities for treatment of thermosolids, saturated porous media, multi-phase flows, and piezoelectric solids.
- Arbitrary Euler-Lagrange description options for fluid and/or fluid-structure(-soil) interaction problems.
- Xfem procedures to model discontinuities, joints, shear bands and cracks growth without need for remeshing.
- Prescribed nodal and/or surface forces options.
- Prescribed nodal displacement, velocity or acceleration options.
- Prescribed arbitrary load-time functions.
- Earthquake acceleration time history generation capability, for earthquake motions compatible with prescribed acceleration response spectra.
- Prescribed consistent free-field motion capability.
- Wave transmitting boundaries.
- Isoparametric data generation schemes (Cartesian, Cylindrical/Polar and Spherical).
- Element birth/death options to model addition (birth) or removal (death) of elements (material) in the physical system.
- Layout optimization analysis capabilities.
- Capability to perform constitutive experiments along prescribed stress and/or strain paths on selected material elements within the finite element mesh.
- Complete restart capabilities with options to selectively change input data.
- Fully integrated interface with the graphical pre- and post-processing program FEMGV (available from TNO DIANA, BV) for both workstation and PC platforms.
- Free input format mode organized into data blocks by means of corresponding macro commands.
- Fully documented user manual.

The element library contains a one-dimensional, two-dimensional, and three-dimensional continuum element with axisymmetric options. An interface element, a contact element, a slide-line element with either perfect friction or frictionless conditions, a slide-line element with Coulomb friction, a truss element, a beam element, a plate/shell element, a membrane element, a boundary element and a link element are also available for two- and three-dimensional analysis.

The material library contains a linear isotropic elastic model, a linear orthotropic elastic model, a nonlinear hyperelastic model, a nonlinear Von Mises viscoelastic model, a diffusive transport model, a linear/nonlinear thermal model, a linear/nonlinear heat conduction model, a linear piezoelectric model, a Newtonian fluid model, a Von Mises elasto(-visco)-plastic model, a Drucker-Prager elasto(‑visco)-plastic model, a Mohr-Coulomb (Matsuoka’s) elasto(-visco)-plastic model, a Cap elasto(-visco)-plastic model, a multi-mechanism (Ishihara’s) elasto-plastic model, and a family of multi-yield elasto(-visco)-plastic models developed by the author.

Dynaflow™ executables are available for supercomputer, workstation and PC computing platforms. Dynaflow™ can be obtained by signing a licensing agreement with Princeton University. A free restricted PC/Windows demo version of Dynaflow™ can be obtained.

Copyright © 1983 Princeton University. This program is proprietary to Princeton University, Princeton, New Jersey. It may only be used as authorized in a license agreement controlling such use.