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Publications (7 of 7) Show all publications
Liu, L. & Becerra, M. (2016). An Efficient Semi-Lagrangian Algorithm for Simulation of Corona Discharges: The Position-State Separation Method. IEEE Transactions on Plasma Science, 44(11), 1-10
Open this publication in new window or tab >>An Efficient Semi-Lagrangian Algorithm for Simulation of Corona Discharges: The Position-State Separation Method
2016 (English)In: IEEE Transactions on Plasma Science, ISSN 0093-3813, E-ISSN 1939-9375, Vol. 44, no 11, p. 1-10Article in journal (Refereed) Published
Abstract [en]

An efficient algorithm without flux correction for simulation of corona discharges is proposed. The algorithm referred to as the position-state separation method (POSS) is used to solve convection-dominated continuity equations commonly present in corona discharges modelling. The proposed solution method combines an Eulerian scheme for the solution of the convective acceleration, the diffusion and the reaction subproblems, and a Lagrangian scheme for the solution of the linear convection subproblem. Several classical numerical experiments in different dimensions and coordinate systems are conducted to demonstrate the excellent performance of POSS regarding low computational cost, robustness, and high-resolution. It is shown that the time complexity of the method when dealing with the convection of charged particles increases linearly with the number of unknowns. For the simulation of corona discharges where local electric fields do not change strongly in time, the time step of POSS could be much larger than the Courant–Friedrichs–Lewy (CFL) time step. These special features enable POSS to have great potential in modeling of corona discharges in long interelectrode gaps and for long simulation times.

Place, publisher, year, edition, pages
IEEE Press, 2016
Keywords
Semi-Lagrangian method; simulation; corona discharges; convection-dominated
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Fusion, Plasma and Space Physics
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-193002 (URN)10.1109/TPS.2016.2609504 (DOI)000388795400001 ()2-s2.0-84991688609 (Scopus ID)
Note

QC 20160928

Available from: 2016-09-24 Created: 2016-09-24 Last updated: 2017-11-21Bibliographically approved
Liu, L. & Becerra, M. (2016). On the dynamics of streamer-to-leader transition in long air gap discharges. In: : . Paper presented at 21st International Conference on Gas Discharges and Their Applications (GD2016). Nagoya, Japan
Open this publication in new window or tab >>On the dynamics of streamer-to-leader transition in long air gap discharges
2016 (English)Conference paper, Published paper (Refereed)
Abstract [en]

In this paper, a self-consistent numerical model is employed to investigate the ionization kinetics of the streamer-to-leader transition in long air gap discharges. The model focuses on the dynamics of the discharge channel in the radial direction using a 1D radial system by taking into account 21 species and 106 chemical reactions. The detailed dynamics of the streamer-to-leader transition after a sequence of streamer bursts, dark periods and aborted leaders are discussed. The calculations are performed for a 1 m long rod-plate configuration using the current measured in experiments reported in the literature. The results show that the average central temperature of a newly formed and a self-propagating stable leader segment is around 2000K and 3000K, respectively. The instant temperature in the gap as a leader segment is incepted can reach 5000K. The predictions of temperature and thermal radius of the leader channel agree well with previous experimental studies.

Place, publisher, year, edition, pages
Nagoya, Japan: , 2016
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-188513 (URN)
Conference
21st International Conference on Gas Discharges and Their Applications (GD2016)
Note

QC 20160711

Available from: 2016-06-12 Created: 2016-06-12 Last updated: 2016-07-11Bibliographically approved
Liu, L. & Becerra, M. (2016). On the transition from stable positive glow corona to streamers. Journal of Physics D: Applied Physics, 49(22), 225202
Open this publication in new window or tab >>On the transition from stable positive glow corona to streamers
2016 (English)In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 49, no 22, p. 225202-Article in journal (Refereed) Published
Abstract [en]

A 2D numerical simulation of the transition from stable positive glow corona to streamers in coaxial cylindrical configuration is presented. The hydrodynamic model with several convection-dominated continuity equations together with Poisson equation are solved with consideration of the ionization layer. The transition from a stable positive glow corona produced under a DC voltage to streamers is investigated under a sudden change of the applied voltage. The critical rate of rise of voltage required for the transition from positive glow to streamer corona is evaluated with a voltage ramp. By introducing either physical or numerical instabilities into the model, streamers with filamentary structures are observed, which produce a sudden increase of the discharge current by more than two orders of magnitude. It is also found that the surface electric field of the corona-generating conductor deviates from the onset electric field, casting doubts about the validity of Kaptzov's approximation to evaluate the transition from stable glow to streamers.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2016
National Category
Electrical Engineering, Electronic Engineering, Information Engineering Fusion, Plasma and Space Physics
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-186204 (URN)10.1088/0022-3727/49/22/225202 (DOI)000377410800010 ()2-s2.0-84971571485 (Scopus ID)
Note

QC 20160510

Available from: 2016-05-04 Created: 2016-05-04 Last updated: 2017-11-30Bibliographically approved
Liu, L. & Becerra, M. (2015). A Parallel Projection Method for the solution of Incompressible Navier-Stokes Equations based on Position-State Separation Method. In: : . Paper presented at 27th International Conference on Parallel Computational Fluid Dynamics, May 17-20, Montreal, Canada.
Open this publication in new window or tab >>A Parallel Projection Method for the solution of Incompressible Navier-Stokes Equations based on Position-State Separation Method
2015 (English)Conference paper, Oral presentation only (Other academic)
Abstract [en]

A simple parallel numerical algorithm with P1/P1 velocity-pressure elements for solving the incompressible Navier-Stokes equations is proposed. In order to circumvent the Babuška-Brezzi condition (i.e. inf-sup condition), a velocity-pressure separation strategy following the idea of projection method is presented. Thus, the velocity and pressure terms are separated using operator-splitting, dividing the problem into two individual governing equations. The velocity equation is solved using an extension form of the position-state separation method (POSS), which has very good performance to solve convection-diffusion-reaction equations. The parallel computation of the method is easy to implement. Classical numerical experiments are conducted which show the efficiency, robustness and accuracy of the method.

Keywords
Projection method, Incompressible flows, Parallel computation
National Category
Computational Mathematics Fluid Mechanics and Acoustics
Research subject
Applied and Computational Mathematics
Identifiers
urn:nbn:se:kth:diva-168197 (URN)
Conference
27th International Conference on Parallel Computational Fluid Dynamics, May 17-20, Montreal, Canada
Funder
StandUp
Note

QC 20150812

Available from: 2015-05-27 Created: 2015-05-27 Last updated: 2015-08-12Bibliographically approved
Liu, L. & Becerra, M. (2015). Two-dimensional Simulation on the Glow to Streamer Transition from Lightning Rods. In: : . Paper presented at 2015 International Symposium on Lightning Protection (XIII SIPDA) (pp. 362-366). IEEE conference proceedings
Open this publication in new window or tab >>Two-dimensional Simulation on the Glow to Streamer Transition from Lightning Rods
2015 (English)Conference paper, Published paper (Refereed)
Abstract [en]

In the past twenty years, there has been a growing concern regarding the effect of space charge produced by glow corona on lightning attachment. Several studies have been reported in the literature to evaluate the generation and drift of space charge generated by glow corona from the top of high grounded objects under thunderstorm conditions, using one (1D) or two (2D) dimensional simulations. Unfortunately, the actual transition from glow corona to streamers cannot be numerically evaluated in these studies since the ionization layer was ignored. Thus, a fully 2D detailed evaluation of the glow corona to streamer transition in air is reported, which considers the non-equilibrium ionization layer around a scaled lightning rod. The transition criterion is obtained by changing the applied voltage with different rise rates (dV/dt) after a stable glow corona is formed. The discharge currents as well as the distributions of positive ions, electrons and electric field during the transition of glow corona to streamers are presented. Based on the simulation results, a case study regarding a real lighting rod under thunderstorms is performed. The analysis indicates that streamers can be incepted in the presence of glow corona from both the tip and body of lightning rods under the influence of distant downward stepped leaders.

Place, publisher, year, edition, pages
IEEE conference proceedings, 2015
Keywords
lightning rod, glow corona, streamer transition, thunderstorm, two-dimensional simulation, ionization layer
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-168317 (URN)10.1109/SIPDA.2015.7339289 (DOI)000382966700067 ()2-s2.0-84962291996 (Scopus ID)978-1-4799-8753-5 (ISBN)
Conference
2015 International Symposium on Lightning Protection (XIII SIPDA)
Funder
StandUp
Note

QC 20160214

Available from: 2015-06-01 Created: 2015-06-01 Last updated: 2017-04-17Bibliographically approved
Liu, L. & Becerra, M. (2014). On the transition from positive glow corona to streamers in air. In: : . Paper presented at 20th International Conference on Gas Discharges and their Applications.
Open this publication in new window or tab >>On the transition from positive glow corona to streamers in air
2014 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

The transition phase from glow to streamer corona is of significant importance for the evaluation of leader discharges initiated from ultra-high voltage power transmission lines under thunderstorms. In order to study the condition required for streamer inception from a glow-corona generating wire, the continuity equations for electrons, positive ions and negative ions coupled with Poisson’s equation are solved. The calculations are performed for a wire-cylinder coaxial configuration in one dimension. The analysis is performed by considering the generation of glow corona under a DC electric field, followed by the transition to a streamer-like ionization wave under a fastchanging electric field ramp. Thus, the critical rate of rise of the applied voltage on the wire surface required for streamer-like structures to initiate in the presence of a stable glow corona is evaluated for different radii and DC voltages.

Keywords
transition, glow corona, streamers
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-166290 (URN)
Conference
20th International Conference on Gas Discharges and their Applications
Funder
StandUp
Note

QC 20150623

Available from: 2015-05-07 Created: 2015-05-07 Last updated: 2015-06-23Bibliographically approved
Liu, L. & Becerra, M. (2014). Two-dimensional simulation on the glow to streamer transition from horizontal conductors. In: : . Paper presented at 2014 International Conference on Lightning Protection (ICLP) (pp. 873-878).
Open this publication in new window or tab >>Two-dimensional simulation on the glow to streamer transition from horizontal conductors
2014 (English)Conference paper, Published paper (Refereed)
Abstract [en]

It has been recently suggested that glow corona generated during thunderstorms could have an important role in the initiation of streamers and upward connecting leaders from power transmission lines. In order to further investigate this, a two-dimensional evaluation of the glow corona generation is here reported, which takes into account the non-equilibrium ionization layer around the conductors. The critical change rate of the background electric field required for the transition from glow corona to streamer initiation is obtained. A numerical strategy to evaluate the glow corona to streamers transition for large gaps and irregular geometries is proposed and validated. A four-bundled conductor is also studied and results showed that when evaluating the critical rate of rise of the background electric field for a bundle conductor during thunderstorms, it could be viewed as a single conductor with the equivalent geometric mean radius of the wire configuration. Last, a study case is performed to estimate the effect of the glow corona on the streamer inception from UHV transmission lines during thunderstorms.

Series
2014 International Conference on Lightning Protection, ICLP 2014 ; 6973247
Keywords
lightning, glow corona; streamer inception; thunderstorm; two-dimensional simulation; ionization layer; UHV transmission lines
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-166302 (URN)10.1109/ICLP.2014.6973247 (DOI)000358572100165 ()2-s2.0-84919822050 (Scopus ID)978-147993544-4 (ISBN)
Conference
2014 International Conference on Lightning Protection (ICLP)
Funder
StandUp
Note

QC 20150623

Available from: 2015-05-07 Created: 2015-05-07 Last updated: 2017-04-17Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5378-701X

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