Initial commit

1 files changed, 48 insertions, 0 deletions

diff --git a/src/navier-stokes.h b/src/navier-stokes.h
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+++ b/src/navier-stokes.h
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+#ifndef NAVIERSTOKES_H
+#define NAVIERSTOKES_H
+
+#include <complex.h>
+#include <fftw3.h>
+
+// to extract elements from array of size S representing a function of momentum, use
+//   array[KEXTRACT(kx,ky,size)]
+#define KLOOKUP(X,Y,S) (X>=0?X:S+X)*S+(Y>=0?Y:S+Y)
+
+
+// parameters for the NS equation
+typedef struct ns_params {
+  // number of modes
+  int K;
+  // 2*K+1
+  int S;
+  // 4*K+1
+  int N;
+  // forcing term
+  _Complex double* g;
+  // time step
+  double h;
+  // friction
+  double nu;
+} ns_params;
+
+// arrays on which the ffts are performed
+typedef struct fft_vects {
+  fftw_complex* fft1;
+  fftw_complex* fft2;
+  fftw_complex* invfft;
+  fftw_plan fft1_plan;
+  fftw_plan fft2_plan;
+  fftw_plan invfft_plan;
+} fft_vects;
+
+// next time step for Irreversible Navier-Stokes equation
+int ins_step(_Complex double* u, ns_params params, fft_vects vects, _Complex double* tmp1, _Complex double* tmp2, _Complex double* tmp3);
+
+// right side of Irreversible Navier-Stokes equation
+int ins_rhs(_Complex double* out, _Complex double* u, ns_params params, fft_vects vects);
+
+// compute alpha
+_Complex double compute_alpha(_Complex double* u, ns_params params);
+
+#endif
+