postProcess/getFacet2D.c

Getting Facets

A utility for extracting interface facets from fluid simulation data.

Description

This program extracts and outputs the facets representing the interface between different phases in a multiphase flow simulation. The facets define the boundary between fluid phases, useful for geometric analysis and visualization of the interface morphology.

Physics Background

In multiphase fluid simulations, interfaces between different fluids are critical features that determine many physical phenomena like surface tension effects, droplet formation, and coalescence events. This utility identifies these interfaces by extracting facets from volume fraction data, allowing for quantitative analysis of interfacial dynamics.

Usage

./getFacets input_file

• Author: Vatsal Sanjay
  [email protected]
  Physics of Fluids Department
  University of Twente

#include "utils.h"
#include "output.h"
#include "fractions.h"

scalar f[];  // Volume fraction field
char filename[80];

Main Function

Loads a simulation snapshot and extracts the interface facets.

• Input parameters:
  • arguments[1]: Filename of the simulation snapshot to process
• Process:
  1. Restores the simulation state from the specified file
  2. Extracts interface facets from the volume fraction field
  3. Outputs facet data to standard error
• Return value:
  • Returns 0 on successful completion
• Note: The facet extraction algorithm identifies where the volume fraction field crosses a threshold value (typically 0.5) between adjacent cells.

int main(int a, char const *arguments[]) {
  sprintf(filename, "%s", arguments[1]);
  restore(file = filename);

  FILE *fp = ferr;
  output_facets(f, fp);
  fflush(fp);
  fclose(fp);

  return 0;
}