Coaxial Disk View Factor Calculator
Calculate direct radiative view factors and black-surface exchange between parallel coaxial disks.
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Result
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Calculation steps
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How to calculate
Apply the parallel coaxial-disk geometry, then use reciprocity A1F12=A2F21 for ideal black-surface direct exchange.
S=1+(R2/R1)²+(gap/R1)²; F12=2(R2/R1)²/(S+√(S²−4(R2/R1)²))
Worked example
Equal-radius disks with separation equal to their radius give F12=F21=(3−√5)/2≈0.381966011.
Assumptions and input details
Infinitely thin parallel concentric facing disks, unobstructed space and ideal black surfaces. Reported heat is direct two-disk exchange only; surrounding surfaces, multiple reflections, gray emissivity and thermal equilibrium are excluded.
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Choose from 23 length definitions, including explicitly labelled regional measures. Area conversions square the length factor; geometric volumes cube it.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
NIST measurement tables · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
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