I tried defining a function that will return the viscosity of water as a function of pressure and temperature. I also tried creating a compiled version. Both seem too slow. Can anybody suggest a way of speeding these up? See code below.

Thanks,
O. Linsuain

In[8]:= (* **** Standard version **** *)
Viscosity[press_, temp_] := 
 QuantityMagnitude[
  ThermodynamicData["Water", 
   "Viscosity", {"Pressure" -> Quantity[press, "Megapascals"], 
    "Temperature" -> Quantity[temp, "Kelvins"]}]]

(* **** Compiled vesion **** *)
ViscosityCompiled = 
 Compile[{press, temp}, 
  QuantityMagnitude[
   ThermodynamicData["Water", 
    "Viscosity", {"Pressure" -> Quantity[press, "Megapascals"], 
     "Temperature" -> Quantity[temp, "Kelvins"]}]]]

Out[9]= CompiledFunction[{11, 12., 5468}, {
Blank[Real], 
Blank[Real]}, {{3, 0, 0}, {3, 0, 1}, {3, 0, 2}}, {}, {0, 0, 3, 0, 0}, \
{{46, 
Function[{press, temp}, 
QuantityMagnitude[
ThermodynamicData[
     "Water", "Viscosity", {
      "Pressure" -> Quantity[press, "Megapascals"], 
       "Temperature" -> Quantity[temp, "Kelvins"]}]]], 3, 0, 0, 3, 0, 
   1, 3, 0, 2}, {1}}, 
Function[{press, temp}, 
QuantityMagnitude[
ThermodynamicData[
   "Water", "Viscosity", {
    "Pressure" -> Quantity[press, "Megapascals"], 
     "Temperature" -> Quantity[temp, "Kelvins"]}]]], Evaluate]

This works fine:

In[10]:= Viscosity[15.0, 400.0]
ViscosityCompiled[15.0, 400.0]

Out[10]= 0.000222455

Out[11]= 0.000222455

But this is too slow with any of the two versions (notice it is only 100 numbers). Interestingly, the first time took about 58 seconds each.

In[12]:= AbsoluteTiming[
 Map[Viscosity[#, 400.0] &, RandomReal[{13.0, 16.0}, 100]];]
AbsoluteTiming[
 Map[ViscosityCompiled[#, 400.0] &, RandomReal[{13.0, 16.0}, 100]];]

Out[12]= {29.9476, Null}

Out[13]= {29.7495, Null}