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Compiling and executing the SPH-SOLVER

The list of requirements for the source code is:

  • A C++20 version
  • The Boost library

To compile the code, the user has to change the working directory to exec/build and then run the following instructions in the terminal:

cmake ../../src

and then:

cmake --build .

This produces an executable file, called SPH-SOLVER, in the exec/build folder. To execute the code, the user needs to run the following:

./SPH-SOLVER

To clean the build directory, the user can use the following command:

cmake --build . --target clean

This will effectively delete the binary from the build directory.

Setting up a case

This program can simulate a range of different scenarios. To set up a case to be run, the user has to set the parameters of the problem by using the .txt files in the exec/input directory. These files specify a number of parameters of the problem. Each line of each file contains the name of the parameter being set, an equals sign, then the value of the parameter. Optionally, these lines may contain comments beginning with # characters, which are ignored by the code.

In case.txt the user can specify the type of initial condition, which specifies the initial configuration of particles. The initial condition (IC) can be one of the following

  • A single particle (ic-one-particle) : to test the correctness of time integration and gravity forcing, as well as the bottom boundary condition.

  • Two particles (ic-two-particles) : to assess the pressure force and viscous terms.

  • Three particles (ic-three-particles) : to assess left and right boundary conditions.

  • Four particles (ic-four-particles) : to assess multiple particle interaction.

  • A Block drop (ic-block-drop): a grid of particles occupying a rectangular region.

  • A Droplet (ic-droplet): particles occupying a circular region.

After selecting the desired IC, the user has to specify its parameters (number and position of the particles) in the homonymous to the IC .txt file. The domain is rectangular and two-dimensional with corners which have coordinates that can be specified in domain.txt. Finally, the constant parameters of the problem which characterize the fluid and the solver set-up can be specified in constants.txt.

The different input files each require different parameters to be set. These are:

  • case.txt defines the simulation configuration:
  • initial condition : init_condition (see above for options)
  • simulation time (s) : T
  • time-step (s) : dt
  • adaptive timestep flag : adaptive_timestep
  • CFL coefficient 1 : coeffCfl1
  • CFL coefficient 2 : coeffCfl2
  • -output frequency : output_frequency

  • constants.txt defines physical constants:

  • radius of influence (m) : h

  • gas constant (J/kg/K) : gas_constant
  • resting density (kg/m) : density_resting
  • viscosity (Pa s) : viscosity
  • acceleration due to gravity (m/s) : acceleration_gravity
  • coefficient of restitution : coeff_restitution
  • domain.txt: defines the dimensions of the domain utilised in the simulation

In addition, depending on the initial condition selected, one of the following files is required:

  • ic-one-particle.txt: sets the initial positions when the selected initial condition is "ic-one-particle"
  • ic-{two, three, four}-particles.txt: sets the initial positions for the corresponding cases
  • ic-block-drop.txt: sets initial conditions for SPH, including the number of particles, the length and width of the block, and the initial axes positions for the center of the block
  • ic-droplet.txt: sets initial conditions for SPH, including the number of particles, the size of the radius of the droplet, and the initial axes positions for the center of the droplet