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   "source": [
    "# Chapter 4: viscosity"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Exa 4.1"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "SI units (Pa s) =  1.00e-03\n",
      " \n",
      " BE units (lbm/ft s) =  6.73e-02\n",
      " \n",
      " Reyns units (reyn) =  1.45e-05\n",
      "press enter key to exit\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "''"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "#At 68F the experimental value of absolute viscosity for water is 1 cp.\n",
    "#What is the equivalent value in (a)SI units (b) BTU and (c)reyns?\n",
    "import math\n",
    "#initialisation of variables\n",
    "V= 1. \t\t\t\t\t\t\t\t#cp\n",
    "#CALCULATIONS\n",
    "#An extra 100 is multiplied to convert poise to lbf s \n",
    "SI= V/100./10. \t\t\t\t\t\t#Pa.s\n",
    "BE= (V*32.2*100/100)/(4.788*100.) \t#lbf s/ft^2\n",
    "RE= V*100/100./(4.788*100*144.) \t#reyn\n",
    "#RESULTS\n",
    "print '%s %.2e' % ('SI units (Pa s) = ',SI)\n",
    "print '%s %.2e' % (' \\n BE units (lbm/ft s) = ',BE)\n",
    "print '%s %.2e' % (' \\n Reyns units (reyn) = ',RE)\n",
    "raw_input('press enter key to exit')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Exa 4.2"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "SI Units (m^2/s) =  1.00e-06\n",
      " \n",
      " British Units (ft/s) =  1.08e-05\n",
      "press enter key to exit\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "''"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "#Determine the kinematic viscosity of water at 68F in (a)SI units (b) BTU\n",
    "import math\n",
    "#initialisation of variables\n",
    "T= 68 \t\t\t\t\t\t\t#F\n",
    "d= 1.0\t\t\t\t\t \t\t#gm/cm^3\n",
    "mu= math.pow(10,-2) \t\t\t#gm/cm s\n",
    "SIm= math.pow(10,-4) \t\t\t#m^2/s\n",
    "m= 10.76 \t\t\t\t\t\t#ft\n",
    "#CALCULATIONS\n",
    "SI= mu*SIm \t\t\t\t\t\t#kinematic viscosity in SI\n",
    "BU= SI*m \t\t\t\t\t\t#kinematic viscosity in BTU\n",
    "#RESULTS\n",
    "print '%s %.2e' % ('SI Units (m^2/s) = ',SI)\n",
    "print '%s %.2e' % (' \\n British Units (ft/s) = ',BU)\n",
    "raw_input('press enter key to exit')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Exa 4.3"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Stoke Units (stoke) =  0.0430\n",
      "press enter key to exit\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "''"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "#Determine the kinematic viscosity of 40 SUS oil.\n",
    "import math\n",
    "#initialisation of variables\n",
    "Ku= 40. \t\t\t\t\t\t#SUS\n",
    "#CALCULATIONS\n",
    "SU= 0.0022*Ku-(1.8/Ku) \t\t\t#stoke units\n",
    "#RESULTS\n",
    "print '%s %.4f' % ('Stoke Units (stoke) = ',SU)\n",
    "raw_input('press enter key to exit')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Exa 4.4"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Re=  2.604e+05\n",
      " \n",
      " Re=   2.604e+05\n",
      "press enter key to exit\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "''"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "#Air at 70F flows through a duct at 50 fps. Calculate the Reynolds number\n",
    "#if the duct is (a) 10 in in diameter (b) 10 in square\n",
    "import math\n",
    "#initialisation of variables\n",
    "v= 50 \t\t\t\t\t\t\t\t\t#fps\n",
    "mu= 1.6*math.pow(10,-4) \t\t\t\t#ft^2/s\n",
    "d1= 10. \t\t\t\t\t\t\t\t#in\n",
    "d2= 10. \t\t\t\t\t\t\t\t#in square\n",
    "#CALACULATIONS\n",
    "D= (math.pi*4*d1*d1/4)/(math.pi*d2*12) \t#Modified diameter\n",
    "Re= (v*D)/mu \t\t\t\t\t\t\t#Reynolds number\n",
    "D1= (d1*d1/(4*d2*3)) \t\t\t\t\t#Modified diameter\n",
    "Re1= (v*D1)/mu \t\t\t\t\t\t\t#Reynolds number\n",
    "#RESULTS\n",
    "print '%s %.3e' % ('Re= ',Re)\n",
    "print '%s %.3e' % (' \\n Re=  ',Re1)\n",
    "raw_input('press enter key to exit')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Exa 4.5"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Q (m^3/s) =  8.77e-07\n",
      "press enter key to exit\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "''"
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "#A fluid with a viscosity of 1.75x 10^-3 pa.s. flows through a tube of 0.5 mm\n",
    "#diameter. if the pressure drop across a 1m length of the tube is 1 MPa, and \n",
    "#the flow is fully developed and laminar, what is the flow rate?\n",
    "import math\n",
    "#initialisation of variables\n",
    "v= 1.75*math.pow(10,-3) \t\t\t\t\t\t\t\t\t#pa s\n",
    "l= 1 \t\t\t\t\t\t\t\t\t\t\t\t\t\t#m\n",
    "P= 1 \t\t\t\t\t\t\t\t\t\t\t\t\t\t#Mpa\n",
    "d= 0.5 \t\t\t\t\t\t\t\t\t\t\t\t\t\t#mm\n",
    "#CALCULATIONS\n",
    "Q= (math.pi*P*1000000.*math.pow(((d/2)/1000.),4))/(l*8*v)\t#Flow rate\n",
    "#RESULTS \n",
    "print '%s %.2e' % ('Q (m^3/s) = ',Q)\n",
    "raw_input('press enter key to exit')"
   ]
  }
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