Smoothed-Particle Hydrodynamics Solver Reference
The Smoothed-Particle Hydrodynamics uses a segregated flow solver approach where a pressure-velocity segregated algorithm is used to enforce mass conservation on the velocity field.
The SPH segregated flow solver is based on the iterative methods that are used in conjunction with its scalable preconditioners. The equations that govern fluid flow are discretized based on the attributes of neighbouring particles.
In SPH flow simulations, the residuals for continuity, momentum, and position automatically monitor and plot the progress of the solver.
Smoothed-Particle Hydrodynamics Solver Properties
- Solver Frozen
- When On, prevents the solver from updating the solution while iterating or responding to other solvers. This feature is primarily a debugging tool and is not supported for normal simulation work.
- Temporary Storage Retained
- When On, Simcenter STAR-CCM+ retains additional field data that the solver generates during an iteration. The particular data retained depends on the solver, and becomes available as field functions during subsequent iterations. Off by default.
Segregated Flow Solver Properties
The segregated flow solver solves the integral conservation equations of mass and momentum in a sequential manner.
- Velocity Solver Time Integration
-
Sets the time integration for the velocity solver.
- Explicit
- Implicit
Velocity
The implicit velocity solver for segregated flow. This solver is particularly suited for modeling highly viscous flows. Allows you to use a larger time-step.
This implicit velocity solver is not available when the Velocity Solver Time Integration is set to Explicit.
- Maximum Iterations
- Specifies the number of iterations for the iterative solver. The solver stops when it reaches the specified number of iterations, regardless of the specified Convergence Tolerance.
- Convergence Option
-
Specifies the method that Simcenter STAR-CCM+ uses for calculating the norm of the residual and the solution increment.
- L2-Norm—calculates the square root of the sum of the squares of the error components. This is the default.
- L1-Norm—calculates the absolute sum of the error components. See Residual Norms.
- Convergence Tolerance
-
Specifies the factor by which the residuals of the linear system must be reduced before the velocity solver stops iterating. For example, with the default convergence tolerance of 1.0E-4, the solver keeps iterating until the residuals of the linear system drop by four orders of magnitude (provided that the specified number of Maximum Iterations is not reached before the convergence tolerance is met).
- Verbosity
-
Specifies the amount of feedback (directed to the output window) by the velocity solver for segregated flow.
- None—the velocity solver for segregated flow runs silently. There is no feedback.
- Low—the residuals of the linear system are printed at the completion of each time-step.
- High—same as Low. Setting the solver verbosity to either Low or High provides feedback on the number of iterations performed by the solvers, allowing you to assess if the linear solver has converged.
- Iterative Method Option
-
Specifies the linear iterative method for the implicit velocity solver.
- Conjugate Gradient—uses the Conjugate Gradient method to accelerate the convergence of the iterative solution of the linear system.
- Bi-Conjugate Gradient Stabilized—uses the Bi-Conjugate Gradient Stabilized to solve nonsymmetric (general) linear systems.
- GMRES—selects the generalized minimal residual for solving large linear systems, suited for sparse and non-symmetric matrices. You are advised to use this method for simulations that are difficult to converge.
- Preconditioning Option
-
When activated, uses a preconditioner for the solver convergence. You are advised not to deactivate this property to avoid divergence.
Pressure
The pressure correction solver for the segregated flow.
- Maximum Iterations
- Specifies the number of iterations for the iterative solver. The solver stops when it reaches the specified number of iterations, regardless of the specified Convergence Tolerance.
- Convergence Option
-
Specifies the method that Simcenter STAR-CCM+ uses for calculating the norm of the residual and the solution increment.
- L2-Norm—calculates the square root of the sum of the squares of the error components. This is the default.
- L1-Norm—calculates the absolute sum of the error components.
- Convergence Tolerance
-
Specifies the factor by which the residuals of the linear system must be reduced before the pressure correction solver stops iterating. For example, with the default convergence tolerance of 0.1, the solver keeps iterating until the residuals of the linear system drop by one orders of magnitude (provided that the specified number of Maximum Iterations is not reached before the convergence tolerance is met).
- Verbosity
-
Specifies the amount of feedback (directed to the console window) by the pressure correction solver for segregated flow.
- None—the pressure correction solver for segregated flow runs silently. There is no feedback.
- Low—the residuals of the linear system are printed at the completion of each time-step.
- High—same as Low. Setting the solver verbosity to either Low or High provides feedback on the number of iterations performed by the solvers, allowing you to assess if the linear solver has converged.
- Iterative Method Option
-
Specifies the linear iterative method for the pressure correction solver.
- Bi-Conjugate Gradient Stabilized—uses the Bi-Conjugate Gradient Stabilized method to solve nonsymmetric (general) linear systems.
- Jacobi—uses the Jacobi iterative technique to solve linear systems of equations, particularly when the coefficient matrix is diagonally dominant.
- GMRES—selects the generalized minimal residual for solving large linear systems, suited for sparse and non-symmetric matrices. You are advised to use this method for simulations that are difficult to converge.
- Preconditioning Option
-
When activated, uses a preconditioner for the solver convergence. You are advised to activate this property to accelerate convergence.