Joukowsky_ops.H

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#ifndef Joukowsky_OPS_H_
#define Joukowsky_OPS_H_
 
#include "amr-wind/wind_energy/actuator/disk/Joukowsky.H"
#include "amr-wind/wind_energy/actuator/disk/disk_ops.H"
#include "amr-wind/utilities/linear_interpolation.H"
#include "amr-wind/utilities/trig_ops.H"
 
namespace amr_wind::actuator::ops {
 
namespace joukowsky {
void parse_and_gather_params(const utils::ActParser& pp, JoukowskyData& data);
inline void
set_current_angular_velocity(JoukowskyData& data, const amrex::Real uInfSqr)
{
    const amrex::Real uInfMag = std::sqrt(uInfSqr);
    data.current_angular_velocity = ::amr_wind::interp::linear(
        data.table_velocity, data.angular_velocity, uInfMag);
}
void prepare_netcdf_file(
    const std::string& name,
    const JoukowskyData& data,
    const ActInfo& info,
    const ActGrid& grid);
 
void write_netcdf(
    const std::string& name,
    const JoukowskyData& data,
    const ActInfo& info,
    const ActGrid& /*unused*/,
    const amrex::Real time);
 
void update_disk_points(Joukowsky::DataType& data);
 
} // namespace joukowsky
 
template <>
struct ReadInputsOp<Joukowsky, ActSrcDisk>
{
    void operator()(Joukowsky::DataType& data, const utils::ActParser& pp)
    {
        auto& meta = data.meta();
        joukowsky::parse_and_gather_params(pp, meta);
        base::do_parse_based_computations<Joukowsky>(data);
    }
};
 
template <>
struct UpdatePosOp<Joukowsky, ActSrcDisk>
{
    void operator()(typename Joukowsky::DataType& data)
    {
 
        if (!data.sim().helics().is_activated()) {
            return;
        }
 
#ifdef AMR_WIND_USE_HELICS
 
        auto& meta = data.meta();
 
        const amrex::Real turbine_direction =
            -data.sim().helics().m_turbine_yaw_to_amrwind[data.info().id] +
            90.0;
        const amrex::Real turbine_direction_radian =
            amr_wind::utils::radians(turbine_direction);
 
        meta.normal_vec[0] = std::cos(turbine_direction_radian);
        meta.normal_vec[1] = std::sin(turbine_direction_radian);
        meta.normal_vec[2] = 0.0;
 
        meta.sample_vec[0] = meta.normal_vec[0];
        meta.sample_vec[1] = meta.normal_vec[1];
        meta.sample_vec[2] = meta.normal_vec[2];
 
        joukowsky::update_disk_points(data);
#endif
    }
};
 
template <>
struct InitDataOp<Joukowsky, ActSrcDisk>
{
    void operator()(typename Joukowsky::DataType& data)
    {
        ops::base::allocate_basic_grid_quantities<Joukowsky>(data);
 
        auto& meta = data.meta();
        meta.tip_correction.resize(meta.num_vel_pts_r);
        meta.root_correction.resize(meta.num_vel_pts_r);
        meta.f_normal.resize(meta.num_vel_pts_r);
        meta.f_theta.resize(meta.num_force_pts);
 
        std::fill(meta.tip_correction.begin(), meta.tip_correction.end(), 1.0);
 
        if (meta.use_root_correction) {
            const amrex::Real dx = 1.0 / meta.num_vel_pts_r;
 
            const auto a = meta.root_correction_coefficient;
            const auto b = meta.root_correction_exponent;
 
            const auto delta = std::max(
                meta.vortex_core_size / meta.radius(),
                vs::DTraits<amrex::Real>::eps());
 
            const auto factor = dx / delta;
 
            for (int i = 0; i < meta.root_correction.size(); ++i) {
                meta.root_correction[i] =
                    1.0 - std::exp(-a * std::pow((i + 0.5) * factor, b));
            }
        } else {
            std::fill(
                meta.root_correction.begin(), meta.root_correction.end(), 1.0);
        }
 
        joukowsky::update_disk_points(data);
    }
};
 
template <>
struct ComputeForceOp<Joukowsky, ActSrcDisk>
{
    void operator()(Joukowsky::DataType& data)
    {
        // Equation comments refer to Sorenson 2020 (full reference above)
        auto& grid = data.grid();
        auto& ddata = data.meta();
        const amrex::Real machine_eps = vs::DTraits<amrex::Real>::eps();
        ddata.disk_force *= 0.0;
 
        const amrex::Real uInfSqr = base::compute_reference_velocity_sqr(ddata);
        const amrex::Real U_ref = std::max(std::sqrt(uInfSqr), machine_eps);
        base::set_thrust_coefficient(ddata, uInfSqr);
        joukowsky::set_current_angular_velocity(ddata, uInfSqr);
 
        const amrex::Real Ct = ddata.current_ct;
        const amrex::Real dx = ddata.dr / ddata.radius();
 
        const ops::base::AreaComputer area(
            ddata.radius(), ddata.num_vel_pts_r, ddata.num_vel_pts_t);
 
        const amrex::Real lambda =
            ddata.radius() * ddata.current_angular_velocity / U_ref;
 
        ddata.current_tip_speed_ratio = lambda;
 
        const amrex::Real lambda_2 = lambda * lambda;
 
        // step 0: compute tip correction based on current wind speed (eq 9)
        if (ddata.use_tip_correction) {
            auto& f = ddata.tip_correction;
            for (int i = 0; i < f.size(); ++i) {
                const auto x = (i + 0.5) * dx;
                f[i] = 2.0 / M_PI *
                       std::acos(std::exp(
                           -0.5 * ddata.num_blades * std::sqrt(1.0 + lambda_2) *
                           (1.0 - x)));
            }
        }
 
        // Compute the solid body term S0 (Sorensen 2022, eq. 27)
        amrex::Real S0 = 0.0;
        const amrex::Real alpha1 = ddata.S0_alpha1;
        const amrex::Real alpha2 = ddata.S0_alpha2;
 
        if (ddata.Ct_rated > 0.0) {
            if (Ct < ddata.Ct_rated) {
                S0 = alpha1 *
                     std::pow((ddata.Ct_rated - Ct) / ddata.Ct_rated, 3.0);
            } else {
                S0 = alpha2 * (ddata.Ct_rated - Ct) / ddata.Ct_rated;
            }
        }
 
        // step 1: compute Ct, a1 and a2 coefficients (eq 16)
        // a3, a4, a5 coefficients are from Sorensen, 2022
        amrex::Real a1 = 0.0;
        amrex::Real a2 = 0.0;
        amrex::Real a3 = 0.0;
        amrex::Real a4 = 0.0;
        amrex::Real a5 = 0.0;
 
        for (int ip = 0; ip < ddata.num_vel_pts_r; ip++) {
            const amrex::Real x =
                amrex::max<amrex::Real>((ip + 0.5) * dx, machine_eps);
 
            a1 += std::pow(ddata.tip_correction[ip], 2.0) *
                  std::pow(ddata.root_correction[ip], 2.0) / x * dx;
 
            a2 += ddata.tip_correction[ip] * ddata.root_correction[ip] * x * dx;
 
            a3 += std::pow(ddata.tip_correction[ip], 2.0) *
                  std::pow(ddata.root_correction[ip], 2.0) * x * dx;
 
            a4 += ddata.tip_correction[ip] * ddata.root_correction[ip] *
                  std::pow(x, 3.0) * dx;
 
            a5 += std::pow(ddata.tip_correction[ip], 2.0) *
                  std::pow(ddata.root_correction[ip], 2.0) * std::pow(x, 3.0) *
                  dx;
        }
 
        // step 2: determine the circulation (q0) from a1, a2 and Ct
        //         (eq. 18, Sorensen, 2022)
 
        //      sqrt[(a2*L+a3*S0)^2+a1*(0.5*Ct-2*a4*L*S0-a5*S0^2)]-(a2*L+a3*S0)
        // q0 = --------------------------------------------------------------
        //                            a1
 
        const amrex::Real term1 = std::pow(a2 * lambda + a3 * S0, 2.0);
        const amrex::Real term2 =
            a1 * (0.5 * Ct - 2.0 * a4 * lambda * S0 - a5 * S0 * S0);
        const amrex::Real term3 = a2 * lambda + a3 * S0;
 
        const amrex::Real numerator = std::sqrt(term1 + term2) - term3;
 
        const amrex::Real denominator =
            amrex::max<amrex::Real>(a1, machine_eps);
 
        const amrex::Real q0 = numerator / denominator;
 
        // step 3: compute normal force (fz) and azimuthal force (f_theta) (eq
        // 13) and cp (eq 20)
 
        VecSlice disk_velocity = ::amr_wind::utils::slice(
            grid.vel, ddata.num_force_pts, ddata.num_force_pts);
 
        amrex::Real moment = 0.0;
 
        int ip = 0;
 
        for (int i = 0; i < ddata.num_vel_pts_r; i++) {
            const amrex::Real& F = ddata.tip_correction[i];
            const amrex::Real& g = ddata.root_correction[i];
 
            const amrex::Real x =
                amrex::max<amrex::Real>((i + 0.5) * dx, machine_eps);
 
            const amrex::Real f_z =
                (q0 / x + S0 * x) * g * F *
                (lambda * x + 0.5 * (q0 / x + S0 * x) * g * F);
 
            ddata.f_normal[i] = f_z;
 
            const auto dArea = area.area_section(i);
 
            for (int j = 0; j < ddata.num_vel_pts_t; j++, ip++) {
                const auto point_current = grid.pos[ip];
 
                // TODO add sign convention for rotation (+/- RPM)
                // Negative sign on theta_vec means turbine is rotating
                // clockwise when standing upstream looking downstream
                const auto theta_vec = -utils::compute_tangential_vector(
                    ddata.center, ddata.normal_vec, point_current);
 
                // normal vec by definition is opposite of the wind direction
                // so we need to flip the sign to give the actual disk velocity
                const amrex::Real u_disk_ij =
                    -ddata.normal_vec & disk_velocity[ip];
 
                const amrex::Real f_theta =
                    u_disk_ij / U_ref * (q0 / x + S0 * x) * g * F;
                ddata.f_theta[ip] = f_theta;
 
                // eq 18
                moment += x * ddata.radius() * f_theta * dArea;
 
                grid.force[ip] =
                    (f_z * ddata.normal_vec + f_theta * theta_vec) *
                    ddata.density * uInfSqr * dArea;
 
                ddata.disk_force = ddata.disk_force + grid.force[ip];
            }
        }
 
        // equation 20
        const amrex::Real eq_20_denominator = amrex::max<amrex::Real>(
            0.5 * M_PI * ddata.density * std::pow(ddata.radius(), 2) *
                std::pow(U_ref, 3),
            machine_eps);
 
        ddata.current_power =
            ddata.density * uInfSqr * moment * ddata.current_angular_velocity;
 
        ddata.current_cp = ddata.density * uInfSqr * moment *
                           ddata.current_angular_velocity / eq_20_denominator;
#ifdef AMR_WIND_USE_HELICS
        if (data.info().is_root_proc && data.sim().helics().is_activated()) {
 
            std::cout << "turbine: " << data.info().id
                      << " jouk power: " << ddata.current_power
                      << " uinfsqr: " << uInfSqr << " moment: " << moment
                      << " ang vel: " << ddata.current_angular_velocity
                      << " normal vec: " << ddata.normal_vec[0] << ' '
                      << ddata.normal_vec[1] << std::endl;
 
            data.sim().helics().m_turbine_power_to_controller[data.info().id] =
                ddata.current_power;
            const amrex::Real turbine_angle = std::atan2(
                ddata.reference_velocity[1], ddata.reference_velocity[0]);
            data.sim()
                .helics()
                .m_turbine_wind_direction_to_controller[data.info().id] =
                270.0 - amr_wind::utils::degrees(turbine_angle);
        }
#endif
    }
};
 
template <>
struct ProcessOutputsOp<Joukowsky, ActSrcDisk>
{
private:
    // cppcheck-suppress uninitMemberVarPrivate
    const Joukowsky::DataType& m_data;
    std::string m_out_dir;
 
    std::string m_nc_filename;
 
    int m_out_freq{10};
 
public:
    // cppcheck-suppress constParameter
    explicit ProcessOutputsOp<Joukowsky, ActSrcDisk>(
        const Joukowsky::DataType& data)
        : m_data(data)
    {}
    void operator()(Joukowsky::DataType& /*data*/) {}
    void read_io_options(const utils::ActParser& pp)
    {
        pp.query("output_frequency", m_out_freq);
    }
    void prepare_outputs(const std::string& out_dir)
    {
        m_nc_filename = out_dir + "/" + m_data.info().label + ".nc";
        joukowsky::prepare_netcdf_file(
            m_nc_filename, m_data.meta(), m_data.info(), m_data.grid());
    }
    void write_outputs()
    {
        const auto& time = m_data.sim().time();
        const int tidx = time.time_index();
        if (tidx % m_out_freq != 0) {
            return;
        }
 
        joukowsky::write_netcdf(
            m_nc_filename, m_data.meta(), m_data.info(), m_data.grid(),
            time.new_time());
    }
};
 
} // namespace amr_wind::actuator::ops
 
#endif /* Joukowsky_OPS_H_ */