assael_1986
===========

M\. J\. Assael, S\. Mixafendi and W\. A\. Wakeham, "The Viscosity and Thermal Conductivity of Normal Hydrogen in the Limit of Zero Density", J\. Phys\. Chem\. Ref\. Data 15, 1315 \(1986\)

`Source record <https://github.com/LupoLab/optmat/blob/main/src/optmat/data/sources/assael_1986.toml>`__ · :doc:`Catalogue </the-data/sources>` · :doc:`Review register </register>`

DOI: `10\.1063/1\.555764 <https://doi.org/10.1063/1.555764>`__

**Source kind:** fit

**Recorded technique:** A correlation of the zero\-density viscosity and thermal conductivity of normal hydrogen from 20 K to 2200 K, from critically evaluated primary measurements, in the form of the kinetic theory of polyatomic gases with a fitted collision functional\.

**Materials in structured entries:** H2

**Dataset quantities:** None recorded.

**Contents:** 0 datasets; 1 formula.

Curation notes
--------------

Identity VALIDATED\_WITH\_WARNINGS by the library\. Printed pp\. 1315\-1322; pages cited are pdf pages \(p\. = pdf page \+ 1314\)\.

THE HYDROGEN VISCOSITY \(pdf p\. 4, Eqs\. 1 and 3, Table 2\)\: eta = \(5/16\) \(m k T / pi\)^\(1/2\) / \(sigma^2 Omega\*\(T\*\)\), ln Omega\* = sum\_{i=0}^{4} a\_i \(ln T\*\)^i, with a = 0\.354125, \-0\.427581, 0\.149251, \-0\.037174, \+0\.003176, sigma = 0\.2968 nm and epsilon/k = 33\.3 K, fitted over 20\-2200 K\. Section 5\.1 \(pdf p\. 7\) gives a different, universal corresponding\-states functional, Eq\. \(13\)\: ln Omega\_eta\* = 0\.46649 \- 0\.57015 ln T\* \+ 0\.19164 \(ln T\*\)^2 \- 0\.03708 \(ln T\*\)^3 \+ 0\.00241 \(ln T\*\)^4, which represents hydrogen's primary data only to 6 %, systematically\.

THE D2 PAPER'S MISPRINT \(TC\-760\)\. Assael, Mixafendi and Wakeham \(1987, assael\_1987\) print this Eq\. \(13\)'s coefficients as their Eq\. \(4\), for 'the viscosity of hydrogen'\. With Eq\. \(3\)'s Table 2 coefficients instead, and their Eq\. \(7\) f\(T\*\) applied at every temperature, their Table 2 of D2 is reproduced within 1\.5 units of its last digit, except the cell at 90 K \(computed 2026\-09\-30, tests/test\_transport\.py\)\. This paper's own Table of hydrogen's viscosity is reproduced by Eqs\. \(1\) and \(3\) to its rounding \(20, 100, 300, 1000 and 2000 K checked\)\.

Only the check is used\: optmat's hydrogen viscosity is Muzny et al\.'s \(muzny\_2013\)\.

**Recorded bibliographic identity status:** VALIDATED\_WITH\_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents.

Datasets
--------

No datasets are recorded.

Formulas
--------

assael\_1986/eq1\_eq3
~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "eq1_eq3",
     "material": "H2",
     "equation": "Eqs. (1) and (3), Table 2, pdf p. 4",
     "printed": "eta = (5/16)(m k T/pi)^(1/2)/(sigma^2 Omega*(T*)); ln Omega* = sum_i a_i (ln T*)^i",
     "variable": "T* = k T / epsilon; eta in Pa s with m in kg, sigma in m",
     "range": "20-2200 K",
     "coefficients": {
       "a0": "0.354125",
       "a1": "-0.427581",
       "a2": "0.149251",
       "a3": "-0.037174",
       "a4": "0.003176",
       "sigma_nm": "0.2968",
       "epsilon_k": "33.3"
     },
     "check": "With the D2 mass and assael_1987's f(T*) at every temperature, reproduces assael_1987's Table 2 within 1.5 units of its last digit except at 90 K (tests/test_transport.py)."
   }

Corrections
-----------

No dataset errata are recorded in this source record.

Formula corrections, where recorded, appear with their formulas above. Curation notes may also discuss corrections or unresolved interpretation. Consult the :doc:`review register </register>` for the checks and decisions.