interest, and have received limited distribution in
computational practice and commercial packages.
For hypoelastic CSD models, the solution to the
problem of increasing the accuracy of numerical
models was presented, [21], and further developed
by him for various models of nonlinear material
behavior in, [22]. It is shown that for hypoelastic
models of media, including those describing
irreversible deformations, and for “predictor-
corrector” schemes with splitting into physical
processes, it is sufficient at the “predictor” stage to
obtain a solution of the linearized equations in the
elastic approximation with the second order of
accuracy. The nonlinear behavior of the material is
taken into account at the “corrector” stage. In this
case, the second order of approximation of the
system of equations as a whole is preserved. In,
[23], [24], a modification of Godunov's scheme for
CSD of the second order of accuracy, monotonic on
discontinuities was proposed. In this case, the exact
solution of the Riemann problem in the elastic
formulation is used for the linearized equations of
the theory of plastic flow by the approach, [21], in a
two-dimensional formulation on a compact stencil.
This modification solved the problem of the
increased scheme viscosity and the problem of
boundary conditions. The increase in accuracy is
achieved due to the convergence of the areas of
influence of the differential and difference problems
of the Riemann problem, the monotonicity of
solutions in the area of discontinuities is ensured by
the transition to the “predictor” of the scheme of the
first order of accuracy. At the "fluid-elastic body"
contact, the exact solution of the Riemann problem
is also used. In, [25], [26], [27], [28], this
modification was generalized to a three-dimensional
case and three-dimensional problems of shock-wave
loading of elastoplastic bodies were solved.
Modeling three-dimensional dynamic processes of
fluid-solid interaction (FSI) in Eulerian variables
also requires an adequate description of complex
processes at moving contact boundaries. Therefore,
it is desirable to highlight and accompany the
moving boundaries in the process of calculations.
Currently, there are two approaches to describe the
spatial motion of free and contact boundaries in
Euler variables. The first approach is (the Sharp
Interface Method - SIM), and the second is (the
Diffusive Interface Method - DIM). The SIM
approach, [29], [30], [31], [32], [33], [34], [35],
[36], [37], involves precise selection and tracking of
the motion of the boundary surface. The best option
is the coincidence of the computational grid with the
boundaries of the body, which is not always
possible in the case of large displacements and
deformations, and, in practice, is possible only in
one-dimensional and two-dimensional cases.
Variants associated with the use of various
algorithms for tracking the location of the contact
surface within moving or stationary Euler grids,
often using the subgrid mesh technique to improve
the accuracy in the most interesting parts of the
computational domain (Adaptive Mesh Refinement
technology -AMR), are also complex and are
successfully applied only to solve two-dimensional
problems. In the 3D case, this approach causes
significant difficulties associated with tracking and
restoring the surface of the bodies itself, dynamic
non-Lagrangian rearrangement of meshes, and the
implementation of boundary conditions. In, [35], a
SIM approach for the 3D case using volume
fractions and solving the Riemann problem of a
"fluid-solid" discontinuity to restore and move the
contact boundary inside cells with a mixture was
proposed. The approach is conservative and
includes AMR, but due to its complexity, it did not
receive further development, even though it
indicated the way to solve the problem. In, [36],
also a SIM variant for the 3D case was proposed.
The authors solve the Riemann problem inside cells
with a mixture by interpolating and extrapolating
parameters from the surrounding cells without a
mixture to formulate and solve the Riemann
problem. Then this solution is used to move the
contact boundary inside the cells with the mixture
and to calculate the fluxes to the surrounding cells,
cutting them by the volume fractions in the cells
with the mixture. Several procedures are iterative.
Also, due to the complexity, the method did not find
further development and application. The work,
[38], is indicative in this respect, evolution from 2D
SIM, [29], [30], [31], [32], [33], to 3D DIM, [38],
[39]. It concludes the practical inapplicability of
SIM for 3D problems. The second DIM approach,
[40], [41], [42], [43], [44], [45], [46], [47], [48],
[49], [50], [51], [52], [53], which is used on
Eulerian grids, does not imply an exact selection of
the contact surface and allows the use of cells
containing mixtures of substances. With this
approach, one has to construct an artificial non-
physical equation of state for the mixture.
Accordingly, it is necessary to construct a solution
WSEAS TRANSACTIONS on FLUID MECHANICS
DOI: 10.37394/232013.2023.18.17
M. H. Abuziarov, E. G. Glazova,
A. V. Kochetkov, S. V. Krylov