AirfoilTable.java

package uk.co.flyingsquirrels.aero;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import uk.co.flyingsquirrels.utils.FileUtils;
import uk.co.flyingsquirrels.utils.MathUtils;

/**
 * Reads and stores polar data from JavaFoil at a fixed (single) Reynold's number
 */
public class AirfoilTable {
	
	private static final String NUMBER = "-?\\d+\\.\\d+";
	private static final Pattern PATTERN = Pattern.compile(String.format("^(%s)\\s+(%s)\\s+(%s)\\s+(%s)", NUMBER, NUMBER, NUMBER, NUMBER));
	
	private static final int ALPHA = 0;
	private static final int CL = 1;
	private static final int CD = 2;
	private static final int CM = 3;
	
	private final String name;
	private final long reynolds;
	
	private final double[][] coeffs;
	private final int dataLength;
	
	public AirfoilTable(String airfoil) {
		List<String> lines = FileUtils.readLines("airfoils/" + airfoil + ".txt");
		name = lines.get(0);
		reynolds = Long.valueOf(lines.get(2).split("=")[1].trim());
		List<Coeff> coeffs = new ArrayList<Coeff>();
		for (String line: lines) {
			readData(line, coeffs);
		}
		
		this.dataLength = coeffs.size();
		this.coeffs = new double[4][dataLength];
		for (int i = 0; i < dataLength; i++) {
			Coeff coeff = coeffs.get(i);
			this.coeffs[ALPHA][i] = MathUtils.toRadians(coeff.getAlpha());
			this.coeffs[CL][i] = coeff.getCl();
			this.coeffs[CD][i] = coeff.getCd();
			this.coeffs[CM][i] = coeff.getCm();
		}
	}
	
	public String getName() {
		return name;
	}
	
	public long getReynolds() {
		return reynolds;
	}
	
	public int getDataLength() {
		return dataLength;
	}
	
	public double[] getAlpha() {
		return coeffs[ALPHA];
	}

	public double[] getCl() {
		return coeffs[CL];
	}

	public double[] getCd() {
		return coeffs[CD];
	}

	public double[] getCm() {
		return coeffs[CM];
	}
	
	private void readData(String line, Collection<Coeff> coeffs) {
		Matcher m = PATTERN.matcher(line);
		if (m.find()) {
			double alpha = Double.parseDouble(m.group(1));
			double cl = Double.parseDouble(m.group(2));
			double cd = Double.parseDouble(m.group(3));
			double cm = Double.parseDouble(m.group(4));
			coeffs.add(new Coeff(alpha, cl, cd, cm));
		}
	}
	
	private class Coeff {
		
		private final double alpha;
		private final double cl;
		private final double cd;
		private final double cm;

		Coeff(double alpha, double cl, double cd, double cm) {
			this.alpha = alpha;
			this.cl = cl;
			this.cd = cd;
			this.cm = cm;
		}

		double getAlpha() {
			return alpha;
		}

		double getCl() {
			return cl;
		}

		double getCd() {
			return cd;
		}

		double getCm() {
			return cm;
		}
	}
}