JDR Vol.17 No.5 pp. 818-828
doi: 10.20965/jdr.2022.p0818


A Consideration on Volcanic Ash Ingress into the Horizontal Air Intake of Air Conditioning

Kiyotoshi Otsuka*,†, Arihide Nobata*, Hitoshi Suwa*, Tomohiro Kubo**, Yousuke Miyagi***, and Masamitsu Miyamura***

*Technology Research Institute, Obayashi Corporation
4-640 Shimo-kiyoto, Kiyose, Tokyo 204-8558, Japan

Corresponding author

**Mount Fuji Research Institute, Yamanashi Prefectural Government, Fujiyoshida, Japan

***National Research Institute for Earth Science and Disaster Resilience (NIED), Tsukuba, Japan

January 15, 2022
May 24, 2022
August 1, 2022
volcanic ash fall, air conditioning, air intake, functional damage, ash ingress

A preliminary consideration is conducted on the amount of vertically falling volcanic ash sucked into the horizontal air intakes of the exterior device for air conditioning (AC) using a numerical calculation code consisting of transport equations of airborne ash concentration, equations of motion of ash particles, and a simplified airflow model. This study focuses on the effect of the inertia force acting on the ash particle on the process of ash ingress into the horizontal air intake of AC. The results with the ash particle of sphericity 0.8 indicate that the inertia force reduces the amount of the ash ingress into the air intake by 22, 31, and 51% for the diameters of 67.5, 125, and 250 μm, respectively, as compared to the case neglecting the inertia force. The ashfall depths (thickness of deposited ash) derived as the ones leading to reduction of the performances of AC from our previous laboratory experiment on an open-type cooling tower are re-evaluated with the code. The results suggest that the ashfall depth affecting AC performances can be larger by a factor of 1.6 to 2.1, depending on the particle sphericity, than that obtained in the experiment where the inertia force was neglected in the conversion from the ash amount provided to the test piece to the “actual” ashfall depth. Simulations on the effect of installing a hood over the air intake are also made, indicating limited but substantial reduction of the expected ash ingress. The importance of mitigating ashfall impacts is stressed.

Cite this article as:
K. Otsuka, A. Nobata, H. Suwa, T. Kubo, Y. Miyagi, and M. Miyamura, “A Consideration on Volcanic Ash Ingress into the Horizontal Air Intake of Air Conditioning,” J. Disaster Res., Vol.17, No.5, pp. 818-828, 2022.
Data files:
  1. [1] E. Fujita, Y. Iriyama, T. Shimbori, E. Sato, K. Ishii, Y. Suzuki, K. Tsunematsu, and K. Kiyosugi, “Evaluation of volcanic hazard risk through numerical simulations,” J. Disaster Res, Vol.14, No.4, pp. 604-615, 2019.
  2. [2] T. M. Wilson, C. Stewart, V. Sword-Daniels, G. S. Leonard, D. M. Johnston, J. W. Cole, J. Wardman, G. Wilson, and S. T. Barnard, “Volcanic ash impacts on critical infrastructures,” Phys. Chem. Earth, Vols.45-46, pp. 5-23, 2012.
  3. [3] S. F. Jenkins, R. J. S. Spence, J. F. B. D. Fonseca, R. U. Solidum, and T. M. Wilson, “Volcanic risk assessment: Quantifying physical vulnerability in the built environment,” J. Volcanol. Geotherm. Res., Vol.276, pp. 105-120, 2014.
  4. [4] N. Miyaji, A. Kan’no, T. Kanamaru, and K. Mannen, “High-resoluton reconstruction of the Hoei eruption (AD 1707) of Fuji volcano, Japan,” J. Volcanol. Geotherm. Res., Vol.207, Nos.3-4, pp. 113-129, 2011.
  5. [5] R. J. Blong, P. Grasso, S. F. Jenkins, C. R. Magill, T. M. Wilson, K. McMullan, and J. Kandlbauer, “Estimating building vulnerability to vocalnic ash fall for insurance and other purposes,” J. Appl. Volcanol., Vol.6, Article No.2, 2017.
  6. [6] S. J. Hampton, J. W. Cole, G. Wilson, T. M. Wilson, and S. Broom, “Volcanic ashfall accumulation and loading on gutters and pitched roofs from laboratory empirical experiments: Implications for risk assessment,” J. Volcanol. Geotherm. Res., Vol.304, pp. 237-252, 2015.
  7. [7] R. Blong, “Building damage in Rabaul, Papua New Guinea, 1994,” Bull. Volcanol., Vol.65, No.1, pp. 43-54, 2003.
  8. [8] S. T. Barnard, “The Vulnerability of New Zealand Lifelines Infrastructure to Ashfall,” Ph.D. thesis, University of Canterbury, pp. 57-104, 2009.
  9. [9] [accessed January 2, 2022]
  10. [10] K. Otsuka, A. Nobata, H. Suwa, T. Kubo, M. Miyamura, and Y. Miyagi, “Experiments on volcanic ash fall impacts on ouside unit and a cooling tower of building air conditioning,” AIJ J. of Technology and Design, Vol.27, No.65, pp. 580-585, 2021 (in Japanese).
  11. [11] K. Otsuka, A. Nobata, H. Suwa, T. Kubo, Y. Miyagi, and M. Miyamura, “Experiments on ashfall impacts on air filters for use in building air conditioning,” Summary of AIJ Annual Meeting, Structural Eng., pp. 29-30, 2021 (in Japanese).
  12. [12] [accessed December 28, 2021]
  13. [13] [accessed December 28, 2021]
  14. [14] L. Connor and C. Connor, “Tephra2 Users Manual,” 2011, [accessed December 28, 2021]
  15. [15] H. F. Schwaiger, R. P. Denlinger, and L. G. Mastin, “Ash3d: A finite-volume, conservative numerical model for ash transport and tephra deposition,” J. Geophys. Res. Solid Earth, Vol.117, No.B4, Article No.B04204, doi: 10.1029/2011JB008968, 2012.
  16. [16] T. Pfeiffer, A. Costa, and G. Macedonio, “A model for the numerical simulation of tephra fall deposits,” J. Volcanol. Geotherm. Res., Vol.140, No.4, pp. 273-294, 2005.
  17. [17] R. A. Dale, “Sedimentation of volcanic ash in the HYSPLIT dispersion model,” CAWCR Technical Report, No.79, p. 3, 2015.
  18. [18] P. Gransdorff and I. Prigogine, “Thermodynamic theory of structure, stability and fluctuations,” Wiley-Interscience, 1971, (Japanese translation, Misuzu Shobo, p. 6, 1977).
  19. [19] A. Costa, A. Folch, and G. Macedonio, “A model for wet aggregation of ash particles in volcanic plumes and clouds: 1. Theoretical formulation,” J. Geophys. Res. Solid Earth, Vol.115, No.B9, Article No.B09201, doi: 10.1029/2009JB007175, 2010.
  20. [20] A. Folch, A. Costa, A. Durant, and G. Macedonio, “A model for wet aggregation of ash particles in volcanic plumes and clouds: 2. Model application,” J. Geophys. Res. Solid Earth, Vol.115, No.B9, Article No.B09202, doi: 10.1029/2009JB007176, 2010.
  21. [21] T. E. Ongaro, A. B. Clarke, B. Voight, A. Neri, and C. Widiwijayanti, “Multiphase flow dynamics of pyroclastic density currents during the May 18, 1980 lateral blast of Mount St. Helens,” J. Geophys. Res. Solid Earth, Vol.117, No.B6, Article No.B06208, 2012.
  22. [22] A. Neri, T. E. Ongaro, G. Macedonio, and D. Gidaspow, “Multiparticle simulation of collapsing volcanic columns and pyroclastic flow,” J. Geophys. Res. Solid Earth, Vol.108, No.B4, Article No.2202, doi: 10.1029/2001JB000508, 2003.
  23. [23] M. H. Dickerson, “MASCON – A mass consistent atmospheric flux model for region with complex terrains,” J. Appl. Meteorol. Climatol., Vol.17, No.3, pp. 241-253, 1978.
  24. [24] G. H. Ganser, “A rational approach to drag prediction of spherical and nonspherical particles,” Powder Technology, Vol.77, No.2, pp. 143-152, 1993.
  25. [25] H. Wadell, “Volume, Shape, and Roundness of Rock Particles,” J. Geol., Vol.40, No.5, pp. 443-451, 1932.
  26. [26] A. Arakawa and V. R. Lamb, “Computational design of the basic dynamical processes of the UCLA general circulation model,” Methods Comput. Phys., Vol.177, pp. 173-165, 1977.

*This site is desgined based on HTML5 and CSS3 for modern browsers, e.g. Chrome, Firefox, Safari, Edge, Opera.

Last updated on Aug. 05, 2022