About

John M. Cimbala is a Professor in the Department of Mechanical Engineering at Penn State University. His research areas include energy systems, thermal and fluid sciences, with specific interests in fluid dynamics, flow visualization, wind tunnels, neutron radiography, turbulence, computational fluid dynamics (CFD), turbulence modeling, turbomachinery, air pollution, stratified tanks, indoor air quality, heat pipes, instrumentation, and hydroturbines. He holds a BS in Aerospace Engineering from The Pennsylvania State University, an MS and PhD in Aeronautics from the California Institute of Technology. Cimbala has contributed extensively to the field through both research and authorship, including co-authoring several textbooks such as 'Fundamentals of Thermal-Fluid Sciences' and 'Fluid Mechanics: Fundamentals and Applications.' His work encompasses experimental, computational, and theoretical studies, with publications spanning journal articles, books, and conference papers. He is actively involved in advancing knowledge in fluid mechanics, energy systems, and turbomachinery, and has made significant contributions to the understanding of turbulent flows, ventilation modeling, and hydropower design.

Research topics

• Computer Science
• Human–computer interaction
• World Wide Web
• Marine engineering
• Simulation
• Structural engineering
• Aerospace engineering
• Multimedia
• Operating system
• Engineering
• Mechanical engineering
• Environmental science

Selected publications

• Ventilation Modeling of a Hen House with Outdoor Access

  Animals · 2025-08-01

  articleOpen accessSenior author

  Outdoor access, often referred to as pop holes, is widely used to improve the production and welfare of hens. Such cage-free environments present an opportunity for precision flock management via best environmental control practices. However, outdoor access disrupts the integrity of the indoor environment, including properly planned ventilation. Moreover, complaints exist that hens do not use the holes to access the outdoor environment due to the strong incoming airflow through the outdoor access, as they behave as uncontrolled air inlets in a negative pressure ventilation system. As the egg industry transitions to cage-free systems, there is an urgent need for validated computational fluid dynamics (CFD) models to optimize ventilation strategies that balance animal welfare, environmental control, and production efficiency. We developed and validated CFD models of a cage-free hen house with outdoor access by specifying real-world conditions, including two exhaust fans, sidewall ventilation inlets, wire-meshed pens, outdoor access, and plenum inlets. The simulations of four ventilation scenarios predict the measured air flow velocity with an error of less than 50% for three of the scenarios, and the simulations predict temperature with an error of less than 6% for all scenarios. Plenum-based systems outperformed sidewall systems by up to 136.3 air changes per hour, while positive pressure ventilation effectively mitigated disruptions to outdoor access. We expect that knowledge of improved ventilation strategy will help the egg industry improve the welfare of hens cost-effectively.

  PublisherOA PDFDOI

• CFD modeling of reactive species air cleaner applications in a classroom

  Indoor Environments · 2024-09-10 · 5 citations

  articleOpen accessSenior author

  Due to increasing concerns related to airborne virus spread indoors, more reactive species air cleaners are being utilized in classrooms. Reactive species generated by air cleaners decompose airborne pathogens chemically, decreasing the risk of infection. Due to the high reactivity of these oxidants, reactive species may be distributed nonuniformly in indoor environments, as are viral aerosols emitted by infectors. Heterogeneous distributions of reactive species may cause spatially non-uniform removal rates of viral aerosols. However, there is little information regarding spatial distributions of either reactive species or viral aerosols in ventilated classrooms. Thus, the objective of this study was to investigate spatial distributions of reactive species and infectious aerosols and to examine how operating conditions of air cleaners affect viral aerosol removal rates. A CFD model simulated the operation of a reactive species air cleaner generating hydrogen peroxide (H 2 O 2 ) in a mechanically ventilated 237 m 3 classroom with nine occupants. The reactive species air cleaner showed a 3–20 times higher equivalent air change rate to a HEPA filter air cleaner with the same inlet and outlet flows. During the operation of reactive species air cleaners, elevated viral aerosol concentration was confined to regions near infectors. This was due to the high reactivity of reactive species, decreasing the infection probability of receptors from 3.2 % to 0.1 % with a 1-hour exposure time. As the room average concentration of reactive species increased from 15.6 to 50.4 ppb, both below the US Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) of 1000 ppb, the room average infection probability decreased from 0.3 % to 0.1 %. Due to the residence times of reactive species, the location of reactive species air cleaners affected the inactivation rate of viral aerosol, resulting in a 24 % variation of concentration difference of infectious aerosol with air cleaner locations.

  PublisherDOI

• Advancements in Hydropower Design and Operation for Present and Future Electrical Demand

  2022-05-09

  bookOpen access1st authorCorresponding

  <p class="MDPI31text" style="text-indent: 0cm;">With current infrastructure, meeting the ever-growing demand for electrical energy across the globe is becoming increasingly difficult. The widespread adoption of both commercial and residential non-dispatchable renewable energy facilities, such as solar and wind, further taxes the stability of the electrical grid, often causing traditional fossil fuel power plants to operate at lower efficiency, and with increased carbon emissions. Hydropower, as a proven renewable energy technology, has a significant part to play in the future global electrical power market, especially as increasing demand for electric vehicles will further amplify the need for dispatchable energy sources during peak charging times. Even with more than a century of proven experience, significant opportunities still exist to expand the worldwide hydropower resources and more efficiently utilize existing hydropower installations. <p class="MDPI31text" style="text-indent: 0cm;">Given this context, this Special Issue of <em>Energies</em> intended to present recent developments and advancements in hydropower design and operation. This Special Issue includes five articles, authored by international research teams from Japan, Pakistan, Sweden, Norway, the United States, and China. The authors bring the collective expertise of government research laboratories, university professors, industry research engineers, computer scientists, and economists. The articles explore advancements in hydroturbine and pump-turbine design, power plant operation, auxiliary equipment design to mitigate environmental damage, and an exploration of community-owned small hydropower facilities.

  PublisherOA PDFDOI

• Numerical Simulation of Airborne Disease Spread in Cage-Free Hen Housing with Multiple Ventilation Options

  Animals · 2022-06-10 · 8 citations

  articleOpen access

  The current ventilation designs of poultry barns have been present deficiencies with respect to the capacity to protect against disease exposure, especially during epidemic events. An evolution of ventilation options is needed in the egg industry to keep pace with the advancing transition to cage-free production. In this study, we analyzed the performances of four ventilation schemes for constraining airborne disease spread in a commercial cage-free hen house using computational fluid dynamics (CFD) modeling. In total, four three-dimensional models were developed to compare a standard ventilation configuration (top-wall inlet sidewall exhaust, TISE) with three alternative designs, all with mid-wall inlet and a central vertical exhaust. A one-eighth scale commercial floor-raised hen house with 2365 hens served as the model. Each ventilation configuration simulated airflow and surrogate airborne virus particle spread, assuming the initial virus was introduced from upwind inlets. Simulation outputs predicted the MICE and MIAE models maintained a reduced average bird level at 47% and 24%, respectively, of the standard TISE model, although the MIRE model predicted comparable virus mass fraction levels with TISE. These numerical differences unveiled the critical role of centrally located vertical exhaust in removing contaminated, virus-laden air from the birds housing environment. Moreover, the auxiliary attic space in the MIAE model was beneficial for keeping virus particles above the bird-occupied floor area.

  PublisherOA PDFDOI

• Correction: Chen et al. Computational Fluid Dynamics Analysis of Alternative Ventilation Schemes in Cage-Free Poultry Housing. Animals 2021, 11, 2352

  Animals · 2022-08-25

  erratumOpen access

  There was an error in the original publication [...].

  PublisherOA PDFDOI

• Advancements in Hydropower Design and Operation for Present and Future Electrical Demand

  Energies · 2022-03-24 · 1 citations

  articleOpen access1st author

  With the current infrastructure, meeting the ever-growing demand for electrical energy across the globe is becoming increasingly difficult [...]

  PublisherOA PDFDOI

• Computational Fluid Dynamics Analysis of Alternative Ventilation Schemes in Cage-Free Poultry Housing

  Animals · 2021 · 23 citations

  • Marine engineering
  • Environmental science
  • Engineering

  /min) in the desired range for cold weather (0 °C). Simulation results and subsequent analyses demonstrated that these alternative models had the capacity to create satisfactory comfortable temperature and air velocity at the hen level. A full-scale CFD model with individual hen models presented robustness in evaluating bird welfare conditions.

  PublisherOA PDFDOI

• Some continuous and discontinuous Galerkin methods and structure preservation for incompressible flows

  International Journal for Numerical Methods in Fluids · 2021-02-23 · 5 citations

  articleOpen accessSenior author

  Abstract In this paper, we present consistent and inconsistent discontinuous Galerkin (dG) methods for incompressible Euler and Navier–Stokes equations with the kinematic pressure, Bernoulli function and EMAC function. Semi‐ and fully discrete energy stability of the proposed dG methods are proved in a unified fashion. Conservation of total energy, linear, and angular momentum is discussed with both central and upwind fluxes. Numerical experiments are presented to demonstrate our findings and compare our schemes with conventional schemes in the literature in both unsteady and steady problems. Numerical results show that global conservation of the physical quantities may not be enough to demonstrate the performance of the schemes, and our schemes are competitive and able to capture essential physical features in several benchmark problems.

  PublisherOA PDFDOI

• Experiential Learning In A Fluid Flow Class Via Take Home Experiments

  2020-09-03 · 7 citations

  article1st author

  This paper describes the development and assessment of a pump flow take-home experiment that was implemented in an introductory junior-level fluid mechanics course in Fall 2005.The takehome experiment, along with appropriate instructions, is assigned as homework.Students borrow the equipment from the department's equipment room, and perform the experiment either at home or in the student lounge or student shop work area.The experimental apparatus consists of a bucket, tape measure, submersible aquarium pump, tubing, measuring cup, and extension cord.Students connect the tube to the pump outlet, submerge the pump in water, and measure the volume flow rate produced at various outflow elevations.They record and plot volume flow rate as a function of outlet elevation, and compare with the manufacturer's pump performance curve (head versus volume flow rate).The homework assignment includes an online pre-test and posttest to assess the change in students' understanding of the principles of pump performance.The results of the assessment support a significant learning gain following the completion of the takehome experiment.These results and analysis of student perception data collected via an online survey embedded in the homework assignment are discussed.

  PublisherDOI

• Computational Fluid Dynamics Modeling of Ventilation and Hen Environment in Cage-Free Egg Facility

  Animals · 2020-06-20 · 13 citations

  articleOpen access

  Poultry facilities are going through an evolution in design due to growing demands for cage-free eggs and egg products without unified guidelines to accommodate these transitions. The goal of this study was to help builders and egg producers assess current ventilation design within cage-free production facilities for conditions that impact hen comfort and welfare. The method of evaluation was simulation of the indoor environment of a hen house via computational fluid dynamics (CFD) modeling with individual hens modeled at a typical stocking density. This paper describes the development of a three-dimensional model of a commercial floor-raised cage-free hen house that is cross-ventilated to document current environmental conditions. A one-eighth section of the barn was modeled at full-scale using existing ventilation schemes with each bird represented by a hen-shaped, heated, solid body. A conventional top-wall inlet, side-wall exhaust (TISE) ventilation configuration was modeled for this study. The simulated ventilation rate for the hen house was approximately 3 m3/h (1.77 ft3/min) per hen resulting in 7092 m3/h (4174 ft3/min) for the 2365 birds, which falls at the higher end of the desired cold weather (0 °C) ventilation range. Contours of airflow, temperature, and pressure were generated to visualize results. Three two-dimensional planes were created at representative cross-sections to evaluate the contours inside and outside the barn. Five animal-occupied zones within each of the model planes were evaluated for practical hen comfort attributes. The simulation output suggested the TISE standard ventilation system could limit air speed to a comfortable average of 0.26 m/s (51 ft/min) and the temperature could be maintained between 18 and 24 °C on average at the bird level. Additionally, the indoor static pressure difference was very uniform averaging −25 Pascal (0.1 inches of water), which falls in the normal range for a floor-raised hen house with negative-pressure ventilation during cold weather conditions. Findings confirmed that CFD modeling can be a powerful tool for studying ventilation system performance at the bird level, particularly when individual animals are modeled, to assure a comfortable indoor environment for animal welfare in poultry facilities.

  PublisherOA PDFDOI

Frequent coauthors

• Hojae Chung

  University of Virginia

  11 shared

• Nathaniel H. Werner

  Liberty University

  11 shared

• Geng Liu

  Baidu (China)

  11 shared

• Bo Cheng

  11 shared

• Junshi Wang

  11 shared

• Alex Wouden

  11 shared

• Haibo Dong

  University of Virginia

  10 shared

• Bryan J. Lewis

  Pennsylvania State University

  8 shared

Labs

• PSMES BoardPI

  The PSMES board of directors is made up of elected officers, six to nine at large members, the ME department head, and a mechanical engineering faculty member.

Education

• Ph.D., Mechanical Engineering

  Pennsylvania State University

  1986

• M.S., Mechanical Engineering

  Pennsylvania State University

  1983

• B.S., Mechanical Engineering

  Pennsylvania State University

  1981